Processes For The Removal Of Rubber From Non-Hevea Plants

ABSTRACT

Provided herein are organic solvent-based processes for the removal of rubber from non- Hevea  plants such as guayule shrubs. By the use of the processes, solid purified rubber can be obtained that contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash, and 0.1-4 weight % resin (when it has been dried so as to contain 0.8 weight % volatile matter).

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/130,050; with a filing date of Apr. 15, 2016, entitled “PROCESSES FORTHE REMOVAL OF RUBBER FROM NON-HEVEA PLANTS,” which is a continuation ofU.S. application Ser. No. 14/383,379; with a filing date of Mar. 6,2013, entitled “PROCESSES FOR THE REMOVAL OF RUBBER FROM NON-HEVEAPLANTS,” which is a national stage of PCT Application Serial No.PCT/US2013/029451, filed Mar. 6, 2013, entitled “PROCESSES FOR THEREMOVAL OF RUBBER FROM NON-HEVEA PLANTS,” which claims priority to andany other benefit of U.S. Provisional Patent Application Ser. No.61/607,448, filed Mar. 6, 2012, entitled “PROCESSES FOR THE REMOVAL OFRUBBER FROM NON-HEVEA PLANTS,” the entire disclosure of which isincorporated by reference herein; U.S. Provisional Patent ApplicationSer. No. 61/607,460, filed Mar. 6, 2012, entitled “PROCESSES FOR THEPURIFICATION OF GUAYULE-CONTAINING SOLUTIONS,” the entire disclosure ofwhich is incorporated by reference herein; U.S. Provisional PatentApplication Ser. No. 61/607,469, filed Mar. 6, 2012, entitled “PROCESSESFOR THE REMOVAL OF BAGASSE FROM A GUAYULE-RUBBER CONTAINING SOLUTION,”the entire disclosure of which is incorporated by reference herein; U.S.Provisional Patent Application Ser. No. 61/607,475, filed Mar. 6, 2012,entitled “PROCESSES FOR RECOVERING RUBBER FROM NON-HEVEA PLANTS USINGBRIQUETTES,” the entire disclosure of which is incorporated by referenceherein; U.S. Provisional Patent Application Ser. No. 61/607,483, filedMar. 6, 2012, entitled “AGED BRIQUETTES CONTAINING PLANT MATTER FROMNON-HEVEA PLANTS AND PROCESSES RELATING THERETO,” the entire disclosureof which is incorporated by reference herein; U.S. Provisional PatentApplication Ser. No. 61/660,991, filed Jun. 18, 2012, entitled “AGEDBRIQUETTES CONTAINING PLANT MATTER FROM NON-HEVEA PLANTS AND PROCESSESRELATING THERETO,” the entire disclosure of which is incorporated byreference herein; U.S. Provisional Patent Application Ser. No.61/661,064, filed Jun. 18, 2012, entitled “PROCESSES FOR THE REMOVAL OFRUBBER FROM NON-HEVEA PLANTS,” the entire disclosure of which isincorporated by reference herein; and U.S. Provisional PatentApplication Ser. No. 61/661,052, filed Jun. 18, 2012, entitled“PROCESSES FOR THE REMOVAL OF RUBBER FROM NON-HEVEA PLANTS,” the entiredisclosure of which is incorporated by reference herein.

BACKGROUND

The Hevea plant or tree (also called Hevea brasiliensis or a rubbertree) is a well-known source of natural rubber (also calledpolyisoprene). Rubber sources such as Hevea brasiliensis, Ficus elastic(India rubber tree) and Cryptostegia grandiflora (Madagascar rubbervine)produce natural rubber in the form of a sap where the rubber issuspended in an aqueous solution that flows freely and can be recoveredby tapping of the plant. Various non-Hevea plants are also known tocontain natural rubber, but their rubber is stored within the individualcells of the plant (e.g., stems, roots or leaves) and cannot be accessedby tapping but can only be accessed by breaking down the cell walls byphysical or other means. Thus, processes for the removal of rubber fromnon-Hevea plants are generally more complicated and entailed thanprocesses for harvesting rubber from Hevea trees.

SUMMARY

Provided herein are organic solvent-based processes for the removal ofrubber from non-Hevea plants. The processes are suitable for use in alaboratory or pilot plant and are scalable to a commercial-size plantthat is designed to collect large quantities of rubber from non-Heveaplants.

In a first embodiment, a method of increasing the rubber recovery fromnon-Hevea plants is provided. The method comprises (A) utilizingbriquettes comprising (i) compressed chopped plant matter having anaverage size of 1.5″ or less, the plant matter comprising bagasse,rubber, resin, and residual water and (ii) no more than 5 weight %leaves from a non-Hevea plant, wherein the briquettes have a densitythat is 40-325% higher than the density of the non-compressed plantmatter; (B) subjecting the briquettes to an organic solvent extractionprocess whereby the briquettes are mixed with at least one polar organicsolvent and at least one non-polar organic solvent to form a slurry thatcontains 0.5-10 weight % water; and (C) processing the slurry to removebagasse and resin and recover at least 95-99% by weight of the rubbercontained within the briquettes.

In a second embodiment, a multi-step process for the removal of rubberfrom guayule plants is provided. In this process, initially, a slurrycontaining (i) plant matter from guayule shrubs (where the plant mattercomprises bagasse, rubber and resin), (ii) at least one non-polarorganic solvent and (iii) at least one polar organic solvent, where (ii)and (iii) are present in amounts at least sufficient to solubilize theresin and rubber from the plant matter is utilized. The slurry contains10-50% by weight plant matter, 50-90% by weight of (ii) and (iii)combined, and 0.5-10 weight % water from the plant matter. A majority ofthe bagasse is removed from the slurry to produce a miscella.Optionally, additional polar organic solvent, non-polar organic solventor a combination thereof (each of which may be the same or differentthan those utilized in the slurry of (a)) is added to the miscella toform a reduced viscosity miscella. The amount of any additional polarorganic solvent that is added to the miscella is less than the amountthat causes the rubber contained within the reduced viscosity miscellato coagulate. Next, 80-95 weight % of bagasse (based on the total weightof bagasse present in the reduced viscosity miscella or in the miscellathat has had a majority of the bagasse removed) is removed from themiscella (either the reduced viscosity miscella resulting from additionof additional solvent(s) or the miscella that has had a majority of thebagasse removed) to form a purified miscella. The majority of bagassethat is removed in this second removal phase has a particle size of lessthan 105 microns. Optionally, the purified miscella is further treatedto remove additional bagasse thereby producing a clarified rubbersolution that contains 0.01-1% by weight bagasse (based on the totalamount of bagasse present in the slurry); 90-99% of the additionalbagasse that is removed has a particle size greater than 45 microns. Therelative amount of polar organic solvent as compared to non-polarorganic solvent within the clarified rubber solution or within thepurified miscella is increased so as to cause the rubber containedwithin to coagulate. From the coagulated rubber, a solid purified rubberis produced. This solid purified rubber is such that when it contains0.8 weight % volatile matter, it also contains 0.05-0.5 weight % dirt,0.2-1.5 weight % ash, and 0.1-4 weight % resin. Multiple aspects of theprocess are conducted at a temperature or temperatures of 10-80° C.(i.e., different aspects of the process may be conducted at the sametemperature or at different temperatures) and a pressure of 35 to 1000kPa.

DETAILED DESCRIPTION

Provided herein are processes for the removal of rubber from non-Heveaplants. For ease of description, the processes are described asembodiments; the use of this terminology is for ease of description onlyand should not be interpreted as limiting upon the disclosed processes.

Definitions

The terminology as set forth herein is for description of theembodiments only and should not be construed as limiting the inventionas a whole.

As used herein, the term non-Hevea plant is intended to encompass plantsthat contain natural rubber within the individual cells of the plant.

As used herein the term “bagasse” is used to refer to that portion ofthe ground or chopped plant matter from a non-Hevea plant that isinsoluble and, hence, is suspended rather than dissolved by organicsolvents. As used herein, bagasse should be understood to include dirtand ash, unless otherwise specified.

As used herein the term “plant matter” means material obtained from anon-Hevea plant. Unless otherwise specified, the plant matter mayinclude roots, stems, bark, woody material, pith, leaves and dirt.

As used herein the term “woody material” means the vascular tissue andmeristematic material obtained from a non-Hevea plant. Unless otherwisespecified, woody material does not include bark.

As used herein the term “bark” refers to the tough outer coveringpresent on the stems and roots of certain (particularly woody orshrub-like) non-Hevea plants and should be understood to include alltissues outside the vascular cambium. Not all non-Hevea plants willcontain bark.

As used herein the term “resin” means the naturally occurring non-rubberchemical entities present in non-Hevea plant matter, including but notlimited to resins (such as terpenes), fatty acids, proteins, andinorganic materials.

As used herein the term “dirt” (such as used in the connection with thesolid purified rubber produced by the processes disclosed herein) meansnon-plant material that may be associated with non-Hevea plants,particularly upon harvesting, such as soil, sand, clay and small stones.Dirt content in solid purified rubber can be determined by completelyre-dissolving the solid rubber and pouring the solution through a 45micron sieve. The sieve is then rinsed with additional solvent anddried. The weight of the material retained on the sieve represents the“dirt” content of the solid purified rubber.

As used herein the term “ash” (such as used in the connection with thesolid purified rubber produced by the processes disclosed herein) meansthe inorganic material (i.e., free of carbon) that remains after ashingthe rubber at 550° C.±25° C.

As used herein, the term “majority” means more than 50% but less than100%. In certain embodiments, the term means 51-60%, and in otherembodiments 60-95%.

As used herein, the phrase “volatile matter” refers to non-rubber matterthat may be contained within a sample of solid-purified rubber, butwhich will volatilize at 100+/−5° C. (or 160+/−5° C. if the rubbersample is suspected to contain volatile hydrocarbon oils). A standardtest for determining the volatile matter that is contained within arubber sample is ASTM D1278-91 (1997).

The Processes

In a first embodiment, a method of increasing the rubber recovery fromnon-Hevea plants is provided. The method comprises (A) utilizingbriquettes comprising (i) compressed chopped plant matter having anaverage size of 1.5″ or less (e.g., ⅛″ to 1.5″ or smaller, as discussedfurther below), comprising bagasse, rubber, resin, residual water and(ii) no more than 5 weight % leaves from a non-Hevea plant, wherein thebriquettes have a density that is 40-325% higher than the density of thenon-compressed plant matter; (B) subjecting the briquettes to an organicsolvent extraction process whereby the briquettes are mixed with atleast one polar organic solvent and at least one non-polar organicsolvent to form a slurry that contains 0.5-10 weight % water; and (C)processing the slurry to remove bagasse and resin and recover at least95-99% by weight of the rubber contained within the briquettes.

In a second embodiment, a multi-step process for the removal of rubberfrom guayule plants is provided. (As explained below, in alternativeembodiments of this process, the plant matter that is utilized is from anon-Hevea plant other than a guayule plant.) Initially, a slurrycontaining (i) plant matter from guayule shrubs (where the plant mattercomprises bagasse, rubber and resin), (ii) at least one non-polarorganic solvent and (iii) at least one polar organic solvent isprepared. The slurry contains 10-50% by weight plant matter, 50-90% byweight of (ii) and (iii) combined, and 0.5-10 weight % water from theplant matter. A majority of the bagasse is removed from the slurry toproduce a miscella. Optionally, additional polar organic solvent,non-polar organic solvent or a combination thereof (each of which may bethe same or different than the solvents utilized in the slurry of (a))is added to the miscella to form a reduced viscosity miscella. Theamount of any additional polar organic solvent that is added to themiscella is less than the amount that causes the rubber contained withinthe reduced viscosity miscella to coagulate. Next, 80-95 weight %bagasse (based upon the total weight of bagasse present in the reducedviscosity miscella or in the miscella that has a majority of the bagasseremoved) is removed from the reduced viscosity miscella or from themiscella which has had a majority of the bagasse removed to form apurified miscella. A majority of the bagasse that is removed (from thereduced viscosity miscella) has a particle size of less than 105microns. Optionally, the purified miscella is further treated to removeadditional bagasse thereby producing a clarified rubber solution thatcontains 0.01-1% by weight bagasse (based on the total amount of bagassepresent in the slurry); 90-99% of the additional bagasse that is removedhas a particle size greater than 45 microns. The relative amount ofpolar organic solvent as compared to non-polar organic solvent withinthe clarified rubber solution or within the purified miscella isincreased so as to cause the rubber contained within to coagulate. Fromthe coagulated rubber, a solid purified rubber is produced. This solidpurified rubber is such that when it contains 0.8 weight % volatilematter, it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ashand 0.1-4 weight % resin. Multiple aspects of the process are conductedat a temperature or temperatures of 10-80° C. (i.e., different aspectsof the process may be conducted at the same temperature or at differenttemperatures) and a pressure of 35 to 1000 kPa.

In certain particular embodiments of the second embodiment, the removalof bagasse in (b) comprises the use of a centrifuge. In such processes,initially, a slurry containing (i) chopped plant matter from guayuleshrubs (where the plant matter contain bagasse, resin and rubber) and(ii) a co-solvent comprised of at least one non-polar organic solventand at least one polar organic solvent, where (i) is present in anamount of 10-50% by weight (based on the total weight of the slurry),(ii) is present in an amount of 50-90% by weight (based on the totalweight of the slurry) and the at least one polar organic solvent ispresent in an amount of 10-40% by weight (based on the total amount ofsolvent) is utilized. (As explained below, in alternative embodiments ofthis process, the plant matter that is utilized is from a non-Heveaplant other than a guayule plant.) The slurry is subjected to acentrifuging in order to remove 70-95% by weight bagasse (based on thetotal weight of bagasse present in the slurry) thereby producing amiscella. Optionally, additional polar organic solvent, non-polarorganic solvent or a combination thereof (each of which may be the sameor different than the organic solvents in the slurry) is added to themiscella to form a reduced viscosity miscella with a viscosity lowerthan 200 centipoise. The amount of any additional polar organic solventthat is added is less than the amount that causes the rubber containedwith the reduced viscosity miscella to coagulate. Depending upon thetype of centrifuge that is utilized when it is desirable to reduce theviscosity of the miscella, it may be possible to add some or all of theadditional solvent directly to the machine(s) performing the extractionprocess so that the miscella exiting the extraction process is a reducedviscosity miscella with a viscosity lower than 200 centipoise. Next,additional bagasse, 80-95 weight % bagasse (based upon the total weightof bagasse present in the reduced viscosity miscella or in the miscellathat has had at least 60% by weight bagasse removed) is removed from thereduced viscosity miscella or from the miscella to form a purifiedmiscella. A majority of the bagasse that is removed in this secondremoval phase (i.e., from the reduced viscosity miscella or from themiscella that has had at least 60% by weight bagasse removed) has aparticle size of less than 105 microns. Optionally, the purifiedmiscella is further treated to remove additional bagasse therebyproducing a clarified rubber solution that contains 0.01-1% by weightbagasse (based on the total weight of bagasse present in the slurry);90-99% of the additional bagasse that is removed (from the purifiedmiscella) has a particle size greater than 45 microns. The relativeamount of polar organic solvent as compared to non-polar organic solventwithin the clarified rubber solution or within the purified miscella isthen increased so as to coagulate the rubber contained therein. Thecoagulated rubber is then isolated from the organic solvent to produce asolid rubber. When this solid rubber contains 0.8 weight % volatilematter, it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ashand 0.1-4 weight % resin. Multiple aspects of the process are conductedat a temperature or temperatures of 10-80° C. (i.e., different aspectsof the process may be conducted at the same temperature or at differenttemperatures) and a pressure of 35-1000 kPa.

In certain particular embodiments of the second embodiment, the removalof bagasse in (b) comprises the use of an extraction decanter.Initially, a slurry containing (i) chopped plant matter from guayuleshrubs (where the plant matter contain bagasse, resin and rubber) and(ii) a co-solvent comprised of at least one non-polar organic solventand at least one polar organic solvent, where (i) is present in anamount of 10-50% by weight (based on the total weight of the slurry),(ii) is present in an amount of 50-90% by weight (based on the totalweight of the slurry) and the at least one polar organic solvent ispresent in an amount of 10-40% by weight (based on the total amount ofsolvent) is utilized. (As explained below, in alternative embodiments ofthis process, the plant matter that is utilized is from a non-Heveaplant other than a guayule plant.) The slurry is subjected to anextraction decanting process (e.g., an extraction decanter) in order toremove 60-95% by weight bagasse (based on the total weight of bagassepresent in the slurry) thereby producing a miscella. Optionally,additional polar organic solvent, non-polar organic solvent or acombination thereof (each of which may be the same or different than theorganic solvents in the slurry) is added to the miscella to form areduced viscosity miscella with a viscosity lower than 200 centipoise(e.g., 10-200 centipoise). The amount of any additional polar organicsolvent that is added is less than the amount that causes the rubbercontained with the reduced viscosity miscella to coagulate. Dependingupon the type of extraction process that is utilized (e.g., anextraction decanter) when it is desirable to reduce the viscosity of themiscella, it may be possible to add some or all of the additionalsolvent directly to the machine(s) performing the extraction process sothat the miscella exiting the extraction process is a reduced viscositymiscalls with a viscosity lower than 200 centipoise. Next, additionalbagasse, 80-95 weight % bagasse (based upon the total weight of bagassepresent in the reduced viscosity miscella or in the miscella that hashad at least 60% by weight bagasse removed) is removed from the reducedviscosity miscella or from the miscella to form a purified miscella. Amajority of the bagasse that is removed in this second removal phase(i.e., from the reduced viscosity miscella or from the miscella that hashad at least 60% by weight bagasse removed) has a particle size of lessthan 105 microns. Optionally, the purified miscella is further treatedto remove additional bagasse thereby producing a clarified rubbersolution that contains 0.01-1% by weight bagasse (based on the totalweight of bagasse present in the slurry); 90-99% of the additionalbagasse that is removed (from the purified miscella) has a particle sizegreater than 45 microns. The relative amount of polar organic solvent ascompared to non-polar organic solvent within the clarified rubbersolution or within the purified miscella is then increased so as tocoagulate the rubber contained therein. The coagulated rubber is thenisolated from the organic solvent to produce a solid rubber. When thissolid rubber contains 0.8 weight % volatile matter, it also contains0.05-0.5 weight % dirt, 0.2-1.5 weight % ash and 0.1-4 weight % resin.Multiple aspects of the process are conducted at a temperature ortemperatures of 10-80° C. (i.e., different aspects of the process may beconducted at the same temperature or at different temperatures) and apressure of 35-1000 kPa.

In certain particular embodiments of the second embodiment, the removalof bagasse in (b) comprises the use of a pressing process. Initially, aslurry containing (i) chopped plant matter from guayule shrubs (wherethe plant matter contain bagasse, resin and rubber) and (ii) aco-solvent comprised of at least one non-polar organic solvent and atleast one polar organic solvent, where (i) is present in an amount of5-50% by weight (based on the total weight of the slurry) and (ii) ispresent in an amount of 50-95% by weight (based on the total weight ofthe slurry) and the at least one polar organic solvent is present in anamount of 10-35% by weight (based on the total amount of solvent) isutilized. (As explained below, in alternative embodiments of thisprocess, the plant matter that is utilized is from a non-Hevea plantother than a guayule plant.) The slurry is subjected to a pressingprocess such as a “dewatering” process with a conveying screw inside aperforated cylinder (e.g., a screw press) in order to remove 51-60weight % of the bagasse (based upon the total weight of the bagasse inthe slurry), thereby producing a miscella. In certain embodiments of thethird embodiment, it may be preferable to subject the bagasse to morethan one round of pressing (e.g., through the screw press) with anadditional amount of co-solvent being added to the bagasse press cakethat is generated from the first pressing, thereby generating a secondslurry that is subjected to another pressing with the two collections ofliquor (the liquid containing the dissolved rubber and resin) beingconsolidated to form the miscella. Optionally, additional polar organicsolvent, non-polar organic solvent or a combination thereof (each ofwhich may be the same or different than the organic solvents in theslurry) is added to the miscella to form a reduced viscosity miscellawith a viscosity lower than 200 centipoise (e.g., 10-200 centipoise).The amount of any additional polar organic solvent that is added is lessthan the amount that causes the rubber contained with the reducedviscosity miscella to coagulate. Next, 80-95 weight % bagasse (basedupon the total weight of bagasse present in the reduced viscositymiscella or in the miscella that has had a 51-60% of the bagasseremoved) is removed from the reduced viscosity miscella or from themiscella to form a purified miscella. A majority of the bagasse that isremoved in this second removal phase (i.e., from the reduced viscositymiscella or the miscella that has had 51-60% of the bagasse removed) hasa particle size of less than 105 microns. Optionally, the purifiedmiscella is further treated to remove additional bagasse therebyproducing a clarified rubber solution that contains 0.01-1% by weightbagasse (based on the total weight of bagasse present in the slurry);90-99% of the additional bagasse that is removed (from the purifiedmiscella) has a particle size greater than 45 microns. The relativeamount of polar organic solvent as compared to non-polar organic solventwithin the clarified rubber solution or within the purified miscella isthen increased so as to coagulate the rubber contained therein. Thecoagulated rubber is then isolated from the organic solvent to produce asolid rubber. When this solid rubber contains 0.8 weight % volatilematter, it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ashand 0.1-4 weight % resin. Multiple aspects of the process are conductedat a temperature or temperatures of 10-80° C. (i.e., different aspectsof the process may be conducted at the same temperature or at differenttemperatures) and a pressure of 35-1000 kPa.

Also provided herein, is a third embodiment wherein an organicsolvent-based method is provided for purifying a solubilized guayulerubber solution that contains at least one non-polar solvent, at leastone polar solvent, solubilized guayule rubber and up to 5-20 weight %bagasse and 0.5-10 weight % water (each based on the total weight of thesolution). (As explained below, in alternative embodiments of thisprocess, the plant matter that is utilized is from a non-Hevea plantother than a guayule plant.) The method (which is conducted at apressure of 35-1000 kPa) comprises centrifuging the solution at a gforce of 500-3,500 to remove at least 90-99% by weight of the bagasse(based upon the total weight of bagasse present in the solution) therebyproducing a purified miscella. A majority of the bagasse that is removed(from the solution) has a particle size of less than 105 microns. Thepurified miscella is then filtered to remove additional bagasse andproduce a clarified rubber solution that contains 0.01-1% by weightbagasse (based on the amount of bagasse in the solution); 90-99% of theadditional bagasse that is removed (from the solution to form theclarified rubber solution) has a particle size greater than 45 microns.

Also provided herein, is a fourth embodiment comprising a process forremoving bagasse from a guayule-rubber containing slurry. As part of theprocess, a slurry containing at least one non-polar organic solvent, atleast one polar organic solvent, and plant matter from a guayule plantsource is utilized. The plant matter comprises 1-15 weight% solubilizedguayule rubber, 70-95 weight% bagasse and 3-20 weight% solubilized resin(As explained below, in alternative embodiments of this process, theplant matter that is utilized is from a non-Hevea plant other than aguayule plant.) Within the slurry, the total amount of nonpolar andpolar organic solvents is 50-90% by weight (based on the total weight ofthe slurry) and the amount of plant matter is 10-50% by weight (based onthe total weight of the slurry). The slurry is moved into a decantercentrifuge that includes a discharge lock and the centrifuge is used toseparate sufficient bagasse from the slurry to produce a miscella thatcontains (i) 60-95 weight % less bagasse than the slurry (based on thetotal amount of bagasse present in the slurry) and (ii) 1-10 weight%solubilized guayule rubber. The process is conducted at a pressure of35-1000 kPa.

Types of Plant Matter/Sources of Bagasse

As previously mentioned, the processes according the first embodimentdisclosed herein are utilized with plant matter from non-Hevea plants.It should also be understood that the second, third, and fourthembodiments, while described in detail with respect to use with guayuleplant matter, could also be utilized in conjunction with certainnon-Hevea plants other than guayule. All descriptions provided hereinwith respect to preparation of plant matter, slurries containing plantmatter, and plant matter containing bagasse that is separated from therubber and resin of the plant matter should be understood to encompassthe use of guayule plant matter (i.e., from guayule shrubs), even if theparticular explanation does not explicitly state that guayule plantmatter is being addressed. Preferably, the processes disclosed hereinare utilized with plant matter from guayule shrubs. Exemplary non-Heveaplants useful in certain embodiments of the first embodiment and incertain embodiments of the second, third and fourth processes disclosedherein, include, but are not limited to: Parthenium argentatum (Guayuleshrub), Taraxacum Kok-Saghyz (Russian dandelion), Euphorbia lathyris(gopher plant), Parthenium incanum (mariola), Chrysothamnus nauseosus(rabbitbrush), Pedilanthus macrocarpus (candililla), Asclepias syriaca,speciosa, subulata, et al (milkweeds), Solidago altissima, graminifoliarigida, et al (goldenrods), Cacalia atripilicifolia (pale Indianplantain), Pycnanthemum incanum (mountain mint), Teucreum canadense(American germander) and Campanula Americana (tall bellflower). Otherplants which produce rubber and rubber-like hydrocarbons are known,particularly among the Compositae, Euphorbiaceae, Campanulaceae,Labiatae, and Moracea families. When removing rubber from plant matterin certain embodiments of each of the first, second, third, and fourthembodiments of the processes disclosed herein, it is contemplated thatone type of plant or a mixtures of more than one type of plant may beutilized. Preferably, according to each of the first, second, third andfourth embodiments disclosed herein, the plant matter utilized is fromguayule shrubs.

In certain embodiments of the processes disclosed herein, the non-Heveaplant matter is obtained from at least one of: Parthenium argentatum(Guayule shrub), Taraxacum Kok-Saghyz (Russian dandelion), Euphorbialathyris (gopher plant), Parthenium incanum (mariola), Chrysothamnusnauseosus (rabbitbrush), Pedilanthus macrocarpus (candililla), Asclepiassyriaca, speciosa, subulata, et al (milkweeds), Solidago altissima,graminifolia rigida, et al (goldenrods), Cacalia atripilicifolia (paleIndian plantain), Pycnanthemum incanum (mountain mint), Teucreumcanadense (American germander) and Campanula Americana (tallbellflower). In certain preferred embodiments according to the first,second, third, and fourth embodiments of the processes disclosed herein,the non-Hevea plant matter is obtained from guayule shrub (Partheniumargentatum).

Preparation of the Plant Matter

When the first, second, third, or fourth embodiments of the processesdisclosed herein make use of plant matter from a guayule shrub, theplant matter that is utilized may take various forms as describedfurther herein. The following discussion in this section should beunderstood to apply equally to the first, second, third and fourthembodiments of the processes disclosed herein. (Briquetting of the plantmatter for use in the first embodiment of the processes disclosed hereinand for use in certain embodiments of the second, third and fourthembodiments disclosed herein, is discussed in a separate section.) Incertain embodiments of the processes disclosed herein, the plant mattercomprises chopped guayule shrub including bark and woody tissue from theshrub but with no more than 5 weight %, preferably no more than 4 weight% or no more than 3 weight % or even more preferably no more than 1weight % of the plant matter comprising leaves from the guayule shrub;in certain embodiments, the amount of plant matter comprising leaves is1-5 weight % and in other embodiments, 0.5-5 weight % or 0.5-1 weight %.In certain of the foregoing embodiments, the guayule shrub used for theplant matter initially comprises both the above-ground portions andbelow-ground portions of the shrub (i.e., the stems (with bark, woodytissue and pith) and the roots). In other of the foregoing embodiments,the guayule shrub used for the plant matter initially comprises only theabove-ground portions of the shrub (in other words, the roots are notincluded in the plant matter). The leaves of the guayule shrub may beremoved using various methods such as field drying followed by shaking.Other methods for removing the leaves from the guayule shrub may occurto those of skill in the art and may be utilized as the particularmethod for removing leaves is not considered to be a significantlimitation of the processes disclosed herein. In certain embodimentswhere the plant matter comprises guayule shrub, the shrubs are harvestedby removing the entire plant (with roots intact) and allowing it to dryin the field to a water content of no more than 20 weight %, preferablyno more than 15 weight % or even no more than 10 weight % water; incertain embodiments, the plant matter comprises 5-20 weight % water,preferably 5-15 weight % water.

In certain embodiments of the processes disclosed herein, the plantmatter utilized in the slurry has been chopped into pieces with anaverage size of 1″ or less. The chipping or chopping may take place inone or more than one step. For example, the non-Hevea plant that isutilized may be rough chopped at the location of harvesting (orelsewhere) into pieces averaging less than 2″ in length. Alternatively,the non-Hevea plant that is utilized may be rough chopped into pieces ofabout 3″ in length. Rough chopping may take place before or after theoptional removal of leaves and soil (such as by shaking the plant orsubjecting it to strong air currents), but is preferably after theremoval of a large majority of leaves and soil from the harvested plantmatter. Chipping or chopping into pieces with an average size of 1.5″ orless or 1″ or less may be achieved using various physical means. Oneexemplary way of obtaining chopped plant matter with an average size of1.5″ or less or 1″ or less is to feed raw plant material (or optionallyrough chopped plant matter) into a shredder, a granulator, a hammer millor a roller mill.

A granulator is a well-known machine designed for chopping or grindingmaterial into various sizes. Most granulators contain multiple knives(often steel knives) and one or more screens (sometimes interchangeable)with various diameter holes to determine the size of the final product.Various size granulators exist and may be useful in chopping the plantmatter such as those containing openings of ⅜″, ¼″ and ⅛″.

A hammer mill can generally be described as a steel drum containing avertical or horizontal rotating shaft or drum on which hammers aremounted along with a surrounding screen-like material on the outersurface; the hammers “pound” the material that is passed through themill. The hammers are generally flat metal bars often with some type ofhardface treatment on the working ends. The hammers may be fixed orswinging. Various size hammer mills exist and may be useful in choppingthe plant matter such as those containing screen openings of ⅜″, ¼″,3/16″ and ⅛″. As the chopped material passes through the screenopenings, the size of the screen openings directly determines the finalparticle size of the hammer milled material.

A roller mill/cracker mill can generally be described as a device withtwo or more rolls each containing longitudinal grooves which assist infurther size reduction of material fed through the mill. Various sizeroller mills exist and may be useful in chopping the plant matter suchas those containing openings of ¾″, ½″, ⅜″, ¼″ and ⅛″. In certainembodiments according to the first, second and third embodiments of theprocesses disclosed herein, the plant matter is subjected to at leastone of a shredder, a granulator, a hammer mill, a roller mill and aflaker mill to produce chopped plant matter having an average size of 1″or less (e.g., ⅛″ to 1″ or ⅛″ to ½″). In other embodiments according tothe first, second and third embodiments of the processes disclosedherein, the plant matter is subjected to at least two of a shredder, agranulator, a hammer mill, a roller mill and a flaker mill to producechopped plant matter having an average size of 1″ or less (e.g., ⅛″ to1″ or ⅛″ to ½″). In yet other embodiments according to the first, secondand third embodiments of the processes disclosed herein, the plantmatter is subjected to shredding/chopping, hammer milling, rollermilling and a flaker mill.

In certain embodiments of the processes disclosed herein, the plantmatter utilized in the slurry (or the source of the bagasse within theslurry) has not only been chopped or shredded (such as by treatment in ashredder, a roller mill, hammer mill and/or granulator) but has alsobeen subjected to a flaker mill/flaker and/or other mechanical treatmentcapable of rupturing the cell walls of the cells that contain thenatural rubber prior to mixing with organic solvents to form a slurry. Aflaker mill or flaker can generally be described as a device with two ormore rolls each having a smooth surface, usually operated at differentspeeds, with a defined and adjustable clearance between rolls whichprimarily assist in providing further rupturing of plant cell walls.Such types of mechanical treatment tend to increase the amount ofnatural rubber that can ultimately be recovered from the plant matter.In certain preferred embodiments of the processes disclosed hereinutilizing plant matter from guayule shrub, chopped plant matter issubjected to both roll milling and flake milling. In those embodimentswhere at least one of roll milling, or hammer milling, a shredder, agranulator and flake milling is used upon the chopped plant matter, thechopped plant matter is preferably treated with at least one antioxidantif the material will be stored prior to preparing the slurry (the amountof the antioxidant being in accordance with the antioxidant discussionherein).

In certain embodiments of the processes disclosed herein, it can behelpful to treat the chopped plant matter with an average size of 1.5″or less or 1″ or less (such as exits a granulator) to remove undersizematerial. The amount of undersize material that is generated may varydepending upon various factors including the method used to chop or chipthe plant material and the speed at which the chopping or grinding takesplace. One exemplary way of removing undersize material is to pass thechopped plant matter over a mesh screen that is then vibrated to allowundersize material to fall through the mesh. Various types of meshscreen may be utilized, depending upon the size of material that isclassified as “undersize.” In certain embodiments, a 30 mesh, 25 mesh,20 mesh, 18 mesh or 16 mesh screen is utilized. The mesh rating of thescreen corresponds to the number of openings per square inch. Hence a 20mesh screen will have 20 openings in one square inch. The sizes of theopenings in the listed mesh screens are as follows: 30 mesh (0.0232″openings or 595 micron openings); 25 mesh (0.0280″ openings or 707micron openings); 20 mesh (0.0331″ openings or 841 micron openings); 18mesh (0.0394″ openings or 1000 micron openings); and 16 mesh (0.0469″openings or 1190 micron openings). Another exemplary way to removeundersize material is by using an air separator which functions to blowaway or out undersize (and hence lighter) particles. Preferably whenundersize material is removed (such as by a mesh screen), at least 90%by weight, even more preferably at least 95% by weight of the undersizematerial is removed. In certain embodiments, the plant material that isused for the slurry has a size of 1/16″ to 1.5″, preferably 1/16 to 1″,even more preferably ⅛″ to ½″; in certain such embodiments the plantmaterial has been subjected to a process such as granulation thatutilizes a screen having opening of 1/16″ ⅛″, ¼″ or ½″ thereby producingmaterial having a maximum size of no bigger than the openings.

In certain embodiments of the first, second, and fourth processesdisclosed herein, the slurry that is utilized contains 10-50 weight %plant matter (based on the total weight of the slurry) with theremaining amount of the slurry comprising organic solvents. (Notably, asdiscussed previously, with respect to the third embodiment of theprocesses disclosed herein, the solution contains 5-20 weight %bagasse.) In addition to the 10-50 weight % plant matter, the slurryalso contains 0.5-10 weight % of water, the water being contributed tothe slurry by the plant matter and included within the 10-50 weight %allotment of plant matter within the slurry. In other words, the 10-50weight % plant matter of the slurry encompasses the water containedwithin in the slurry. In certain embodiments according to the first,second and fourth embodiments of the processes described herein, theslurry that is utilized contains 25-50 weight % plant matter (based onthe total weight of the slurry) with the remaining amount of the slurrycomprising organic solvents. These limitations as to the amount of plantmatter used within the slurry apply to those embodiments of the first,second and fourth embodiments of the processes described herein wherethe plant matter is from a non-Hevea plant and particularly to thosewhere the plant matter is from a guayule shrub.

As previously discussed, according to the first, second and fourthembodiments of the processes described herein, the plant matter utilizedin the slurry provides bagasse, rubber and resin. (Notably, in the thirdembodiment of the processes disclosed herein, the solubilized guayulerubber solution also contains bagasse, rubber and resin along withorganic solvents.) The solubilized guayule rubber solution of the thirdembodiment has less bagasse (5-20%) as compared to certain of the otherembodiments (10-50%) either because less plant matter has been addedrelative to the organic solvents or, more preferably, because someamount of bagasse has already been removed to create the solubilizedguayule rubber solution.) The rubber and resin that are contained withinthe slurry are solubilized by the at least one non-polar organic solventand at least one polar organic solvent, respectively. In certainembodiments according to the first, second and fourth embodiments of theprocesses described herein, the plant matter utilized in the slurryincludes bark, woody material, rubber and resin. In certain embodimentsaccording to the first, second, and fourth embodiments of the processesdescribed herein, woody material comprises at least 80 weight %, atleast 85 weight % or even at least 90 weight % of the plant matter andthe remaining plant matter comprises bark and leaves; in certain suchembodiments, the woody material comprises 80-100%, 80-95% or 90-100% or90-99% of the plant matter. In order to achieve the foregoing make-up ofplant matter it may be necessary to remove or limit the amount of barkand leaves that is utilized within the plant matter. In yet otherembodiments according to the first, second and fourth embodiments of theprocesses described herein, bark comprises at least 50 weight %, atleast 60 weight %, at least 70 weight % or even at least 80 weight % ofthe plant matter and the remaining plant matter comprises woody materialand leaves; in certain such embodiments, the bark comprises 50-100%,50-95% or 70-100% or 70-99% of the plant matter. These limitations as tothe amount of plant matter used within the slurry apply to thoseembodiments of the first, second, and fourth embodiments of theprocesses described herein where the plant matter is from a non-Heveaplant and particularly to those where the plant matter is from a guayuleshrub. In order to achieve the foregoing make-up of plant matter it willlikely be necessary to remove or limit the amount of woody material andleaves that is utilized within the plant matter that goes into theslurry. Each portion of the plant matter (i.e., bark, woody material andleaves) will contain varying amounts of rubber, resin and water.

In certain embodiments, the slurry utilized in the first, second, andfourth embodiments of the processes described herein contains 0.5-10weight % water. While the processes described herein are organic solventbased, some small residual amount of water (i.e., 0.5-10 weight %) maybe present (primarily from residual water contained within the plantmatter, although a small amount may be contributed by residual waterwithin the organic solvents). In certain embodiments according to thefirst, second, and fourth embodiments of the processes described herein,the slurry contains 0.5-7 weight % water, 0.5-5 weight % water or even0.5-2 weight % water. In certain embodiments according to the first,second, and fourth embodiments of the processes described herein, theslurry contains no more than 4 weight % water, no more than 3 weight %water or even no more than 2 weight % water. In preferred embodiments ofthe first, second and fourth embodiments of the processes disclosedherein, the slurry preferably contains no bleaching agent, defoamingagent or organic protein-denaturing compound. In preferred embodiment ofthe third embodiment of the processes disclosed herein, the solubilizedguayule rubber solution contains no bleaching agent, defoaming agent ororganic protein-denaturing compound.

Utilization of Briquetted Plant Matter

The following description of briquetted plant matter should beunderstood to be applicable to not only the first embodiment of theprocesses disclosed herein but also to certain embodiments of the secondembodiment of the processes disclosed herein (i.e., when the secondembodiment utilizes plant matter in briquetted form to form the slurry).

Preparation of the Plant Matter for Briquettes

In certain embodiments of the processes disclosed herein, the briquettesare made from plant matter that has been chopped or chopped into pieceswith an average size of 1″ or less. Generally, the chipping or choppingof the plant matter to a size of 1.5″ or less or 1″ or less may takeplace in one or more than one step. For example, the non-Hevea plantthat is utilized may be rough chopped at the location of harvesting intopieces averaging less than 2″ in length. Rough chopping may take placebefore or after the optional removal of leaves and soil (such as byshaking the plant or subjecting it to strong air currents), but ispreferably after the removal of a large majority of leaves and soil fromthe harvested plant matter. Chipping or chopping into pieces with anaverage size of 1.5″ or less or 1″ or less may be achieved using variousphysical means. One exemplary way of obtaining chopped plant matter withan average size of 1.5″ or less or 1″ or less is to feed raw plantmaterial (or optionally rough chopped plant matter) into a shredder, agranulator, a hammer mill or a roller mill. A granulator is a well-knownmachine designed for chopping or grinding material into various sizes.Most granulators contain multiple knives (often steel knives) and one ormore screens (sometimes interchangeable) with various diameter holes todetermine the size of the final product. Various size granulators existand may be useful in chopping the plant matter such as those containingopenings of ⅜″,¼″ and ⅛″. A hammer mill can generally be described as asteel drum containing a vertical or horizontal rotating shaft or drum onwhich hammers are mounted; the hammers “pound” the material that ispassed through the mill. Various size hammer mills exist and may beuseful in chopping the plant matter such as those containing openings of⅜″, ¼″ and ⅛″. A roller mill/cracker mill can generally be described asa device with two or more rolls each containing longitudinal grooveswhich assist in further size reduction of material fed through the mill.Various size roller mills exist and may be useful in chopping the plantmatter such as those containing openings of ⅜″, ¼″ and ⅛″. In certainembodiments according to the first and second embodiments of theprocesses disclosed herein, the plant matter is subjected to at leastone of a granulator, a shredder, a hammer mill, a roller mill and aflaker mill to produce chopped plant matter having an average size of 1″or less”. In other embodiments according to the first and secondembodiments of the processes disclosed herein, the plant matter issubjected to at least two of a shredder, a granulator, a hammer mill, aroller mill and a flaker mill to produce chopped plant matter having anaverage size of 1″ or less.

In certain embodiments of the processes disclosed herein, the plantmatter utilized in the briquettes has not only been chopped or shredded(such as by treatment in a shredder, a roller mill, hammer mill and/orgranulator) but has also been subjected to a flaker mill/flaker and/orother mechanical treatment capable of rupturing the cell walls of thecells that contain the natural rubber after briquetting but prior tobeing mixed into the slurry. A flaker mill or flaker can generally bedescribed as a device with two or more rolls each having a smoothsurface, usually operated at different speeds, with a defined andadjustable clearance between rolls which primarily assist in providingfurther rupturing of plant cell walls. Such types of mechanicaltreatment tend to increase the amount of natural rubber that canultimately be recovered from the plant matter. In certain preferredembodiments of the first and second embodiments of the processesdisclosed herein utilizing plant matter from guayule shrub, choppedplant matter is subjected to both roll milling and flake milling. Inother embodiments, chipped plant matter from the guayule shrub is usedfor the briquettes, and the chopped plant matter is subjected to atleast one of roll milling, a shredder, a granulator and hammer millingprior to compression into a briquette and flake milling afterbriquetting (during but before preparation of the slurry). In thoseembodiments where at least one of roll milling, or hammer milling, ashredder, a granulator and flake milling is used upon the chopped plantmatter, the chopped plant matter is preferably treated with at least oneantioxidant prior to being compressed into a briquette (the amount ofthe antioxidant being in accordance with the previous antioxidantdiscussion).

In certain embodiments according to the first and second embodiments ofthe processes disclosed herein, it can be helpful to treat the choppedplant matter with an average size of 1.5″ or less or 1″ or less (such asexits a granulator) to remove undersize material before briquetting. Theamount of undersize material that is generated may vary depending uponvarious factors including the method used to chop or chip the plantmaterial and the speed at which the chopping or grinding takes place.One exemplary way of removing undersize material is to pass the choppedplant matter over a mesh screen that is then vibrated to allow undersizematerial to fall through the mesh. Various types of mesh screen may beutilized, depending upon the size of material that is classified as“undersize.” In certain embodiments, a 30 mesh, 25 mesh, 20 mesh, 18mesh or 16 mesh screen is utilized. The mesh rating of the screencorresponds to the number of openings per square inch. Hence a 20 meshscreen will have 20 openings in one square inch. The sizes of theopenings in the listed mesh screens are as follows: 30 mesh (0.0232″openings or 595 micron openings); 25 mesh (0.0280″ openings or 707micron openings); 20 mesh (0.0331″ openings or 841 micron openings); 18mesh (0.0394″ openings or 1000 micron openings); and 16 mesh (0.0469″openings or 1190 micron openings). Another exemplary way to removeundersize material is by using an air separator which functions to blowaway or out undersize (and hence lighter) particles. Preferably whenundersize material is removed (such as by a mesh screen), at least 90%by weight, even more preferably at least 95% by weight of the undersizematerial is removed. In certain embodiments, the plant material that isformed into briquettes has a size of 1/16″ to 1.5″, preferably 1/16 to1″, even more preferably ⅛″ to ½″; in certain such embodiments the plantmaterial has been subjected to a process such as granulation thatutilizes a screen having opening of 1/16″ ⅛″, ¼″ or ½″ thereby producingmaterial having a maximum size of no bigger than the openings.

In certain embodiments, the plant matter that is compressed into thebriquettes has not only been chipped but has also been subjected to aroller mill/cracker mill, flaker mill/flaker, hammer mill and/or othermechanical treatment capable of rupturing the cell walls of the cellsthat contain the natural rubber. A roller mill/cracker mill cangenerally be described as a device with two or more rolls eachcontaining longitudinal grooves which assist in further size reductionof material fed through the mill. A flaker mill or flaker can generallybe described as a device with two or more rolls each having a smoothsurface, usually operated at different speeds, with a defined andadjustable clearance between rolls which primarily assist in providingfurther rupturing of plant cell walls. A hammer mill can generally bedescribed as a steel drum containing a vertical or horizontal rotatingshaft or drum on which hammers are mounted; the hammers “pound” thematerial that is passed through the mill. Such types of mechanicaltreatment tend to increase the amount of natural rubber that canultimately be recovered from the plant matter. In certain embodiments,chipped plant matter from the guayule shrub is used for the briquettes,and the chipped plant matter is subjected to at least one of rollmilling, flake milling and hammer milling prior to compression into abriquette. In those embodiments where at least one of roll milling,flake milling or hammer milling is used upon the chipped plant matter,the chipped plant matter is preferably treated with at least oneantioxidant prior to being compressed into a briquette (the amount ofthe antioxidant being in accordance with the antioxidant discussionherein).

The briquettes that are used in the embodiments described herein maycontain a certain amount of water. In certain embodiments, thebriquettes contain 2-20% by weight water (based upon the total weight ofthe briquette). In other embodiments the briquettes contain 5-15% byweight water. The water that is within the briquettes has as its primarysource residual water from the plant matter. The amount of water presentin the briquettes can be adjusted such as by drying the chipped plantmatter prior to compacting it into briquettes. In certain embodiments ofthe first and second embodiments described herein, the chipped plantmatter is dried to reduce its moisture content by at least 2 weight %,by at least 4 weight % or even by at least 6 weight % prior tocompacting the plant matter into briquettes. Various methods ofachieving drying of the chopped plant matter can be utilized, including,but not limited to, sun drying, forced air drying (with air that is dryand/or heated). In certain embodiments, the plant matter may be driedprior to chipping. Another potential source for the water that may bepresent in the briquettes is additives added to the plant matter afterharvest. As discussed in more detail later, these additives can includeantioxidants and/or binders that may optionally be applied via aqueoussolutions of the active ingredients.

When the embodiments disclosed herein make use of briquettes made ofplant matter from a guayule shrub, the plant matter that is utilized maytake various forms as described further herein. In certain embodiments,the plant matter comprises chopped guayule shrub including bark andwoody tissue from the shrub but with no more than 5 weight %, preferablyno more than 4 weight % or no more than 3 weight % or even morepreferably no more than 1 weight % of the plant matter comprising leavesfrom the guayule shrub. In certain of the foregoing embodiments, theguayule shrub used for the plant matter initially comprises both theabove-ground portions and below-ground portions of the shrub (i.e., thestems (with bark, woody tissue and pith) and the roots). In other of theforegoing embodiments, the guayule shrub used for the plant matterinitially comprises only the above-ground portions of the shrub (inother words, the roots are not included in the plant matter). The leavesof the guayule shrub may be removed using various methods such as fielddrying followed by shaking. Other methods for removing the leaves fromthe plant matter of the guayule shrub before incorporating that plantmatter into briquettes may occur to those of skill in the art and may beutilized as the particular method for removing leaves is not consideredto be a significant limitation of the processes disclosed herein.

In certain embodiments, the plant matter utilized in the briquettescontains bagasse, rubber and resin. In certain embodiments, the plantmatter utilized in the briquettes includes bark, woody material, rubberand resin. In certain embodiments, woody material comprises at least 70weight %, 80 weight %, at least 85 weight % or even at least 90 weight %of the briquette and the remaining amount of the briquette comprisesbark and leaves. In order to achieve the foregoing make-up of plantmatter within the briquette it may be necessary to remove or limit theamount of bark and leaves that is utilized within the plant matter andcompacted into briquettes. In yet other embodiments, bark comprises atleast 50 weight %, at least 60 weight %, at least 70 weight % or even atleast 80 weight % of the briquettes and the remaining amount of thebriquettes comprise woody material and leaves. In order to achieve theforegoing make-up of plant matter within the briquettes it will likelybe necessary to remove or limit the amount of woody material and leavesthat is utilized within the plant matte and compacted into briquettes.In certain embodiments, the briquettes comprise at least 80% by weightbark, less than 20% by weight woody material and less than 1 weight %leaves. In order to achieve the foregoing make-up of plant matter withinthe briquettes it will likely be necessary to remove or limit the amountof woody material and leaves that is utilized within the plant matterand compacted into briquettes. In yet other embodiments, the briquettescontain less than 5 weight % or less woody material, with the remainingamount of the briquettes comprising up to 95 weight % bark andpreferably less than 2 weight % leaves, even more preferably less than 1weight % leaves. Each portion of the plant matter (i.e., bark, woodymaterial and leaves) used within the briquettes will contain varyingamounts of bagasse, rubber, resin and water.

Briquetting

As previously discussed, certain embodiments disclosed herein make useof compressed plant matter in the form of briquettes. The term briquetteis meant to encompass various forms or shapes, including, but notlimited to, pellets, cubes, rectangular solids, spherical solids,egg-shaped solids, bricks and cakes. Various methods exist forcompacting the plant matter into briquettes. One method of preparingbriquettes from the plant matter is to utilize a commercial briquettingmachine to prepare the briquettes. Various companies manufacture thesemachines and they are available in various sizes and specifications.Exemplary briquetting machines include those manufactured by K.R.Komarek, Inc. (Wood Dale, Ill.), including the roll-type briquettingmachines model no. B 100R and BR200QC. Generally, a briquetting machineutilizes a roll-type system to compact material, with or without theaddition of a binder to the material that is being compressed. Pressurecan be applied by the machine in varying amounts depending upon themachine utilized, the properties of the chipped plant matter and theproperties desired in the briquettes. In certain embodiments, briquettesof plant matter from a guayule shrub are made using a briquettingmachine. In certain of the foregoing embodiments, a binder is applied tothe chipped plant matter prior to its being compressed into briquettes.Other methods of preparing briquettes of chipped plant matter fromnon-Hevea plants may occur to those of skill in the art and may beutilized within the scope of the processes disclosed herein.

In certain embodiments, the briquettes are made from chipped plantmatter that has been treated with one or more binders prior tocompression into briquettes. Various types of binders may be utilized,including, but not limited to, organic-based binders (such as woodproducts, clay, starches and ash), chemical-based binders (such as-sulfonate, lime, and sodiumbentonite and liquids such as water. Theamount of binder utilized with the chipped plant matter may varydepending upon the type of briquette being formed. In certainembodiments, the amount of binder utilized with the briquette 0.1-5weight % (based on the total weight of the briquette).

In certain embodiments, the briquettes are made from chipped plantmatter that has been treated with one or more antioxidants prior tocompression into briquettes. Suitable compounds for use as the one ormore antioxidants in certain embodiments according to the first andsecond embodiments disclosed herein are well known to those skilled inthe art and include, but are not limited to,2,6-di-t-butyl-4-methylphenol (also known as 2,6-di-t-butyl-p-cresol);N-(1,3-dimethylbutyl)-N′-phenyl-1,4-benzenediamine;octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate (commerciallyavailable as Irganox® 1076); 4,6-bis (octylthiomethyl)-o-cresol(commercially available as Irganox® 1520), monohydric hindered phenolssuch as 6-t-butyl-2,4-xylenol, styrenated phenols, butylatedoctylphenols; bisphends, for example4,4′-butylidenebis(6-t-butyl-m-cresol), polybutylated bisphenol A,hindered hydroquinones such as 2,4-di-t-amylhydroquinone; polyphenols,such as butylated p-cresol-dicyclopentadiene copolymer; phenolicsulfides such as 4,4′-thiobis(6-t-butyl-3-methyl-phenol),alkylated-arylated bisphenol phosphites such astris(nonylphenyl)phosphite, triazinetriones such as alkylatedhydroxycinnamate triester of tris(2-hydroxyethyl)-triazinetrione,tris(alkyhydroxybenzyl)-triazinetrione; pentaerythritol esters such astetrakis(methylene-3,5-di-t-butyl-4-hydroxyhydrocinnamate)-methane;substituted diphenylamines such as octylated diphenylamines,p-(p-touenesulfonamido)-di-phenylamine, nonylated diphenylamine,diisobutylene-diphenylamine reaction products; dihydroquinolines such as6-dodecyl-1,2-dihydro-2,2,4-trimethylquinoline; dihydroquinolinepolymers such as 1,2-dihydro-2,2,4-trimethylquinoline polymer;mercaptobenz-imidazoles such as 2-mercaptobenzimidazole; metaldithiocarbamates such as nickel dibutyldithiocarbamate, nickeldiisobutyldithiocarbamate, nickel dimethyldithiocarbamate;ketone/aldehyde-arylamine reaction products such asaniline-butyraldehyde condensation products, diarylamine-ketone-aldehydereaction products; and substituted p-phenylenediamines such asdi-b-naphthyl-p-phenylenephenylenediamine andN-phenyl-N′-cyclohexyl-p-phenylenediamine. The total amount of theantioxidant employed in those embodiments according to the first andsecond embodiments disclosed herein that utilize at least oneantioxidant may be in the range of 0.2% to 2% by weight of the purifiedsolid rubber ultimately produced by the process (based upon the weightof the purified solid rubber containing 0.8 weight % volatile matter).

In certain embodiments, the briquettes are capable of being stored forat least 90 days after compacting while still having the rubbercontained within the briquettes retain a molecular weight of at least800,000, preferably at least 1,000,000. In certain preferredembodiments, the briquettes are made of chipped plant matter from aguayule shrub and the briquettes are capable of being stored for atleast 90 days after compacting while still having the rubber containedwithin the briquettes retain a molecular weight of at least 800,000,preferably at least 1,000,000. In other embodiments, the briquettes arecapable of being stored for at least 7 months (210 days) aftercompacting while still having the rubber contained within the briquettesretain a molecular weight of at least 800,000, preferably at least1,000,000. In certain preferred embodiments, the briquettes are made ofchipped plant matter from a guayule shrub and the briquettes are capableof being stored for at least 7 months (210 days) after compacting whilestill having the rubber contained within the briquettes retain amolecular weight of at least 800,000, preferably at least 1,000,000.

Preparation of the Slurry

Depending upon how the initial slurry (containing plant matter from anon-Hevea plant, at least one polar organic solvent and at least onenon-polar organic solvent) has been prepared or processed, in certainembodiments of the first, second, third, and fourth embodiments of theprocesses disclosed herein, the overall extraction of rubber from thenon-Hevea plant matter may be enhanced by ensuring that the non-Heveaplant matter is not only thoroughly contacted with the solvents but alsoby agitating or mixing the combination of plant matter and solvents.Various methods of mixing and/or applying agitation to the combinationof plant matter and solvents may be utilized, including, but not limitedto mixing in an agitated tank, homogenizing, dispersing and wet-milling.In certain such embodiments, one or more tanks or reactors may beutilized to apply mixing and/or agitation to the slurry or to thecombination of plant matter and solvents either prior to utilizing theslurry or at least prior removing the majority of the bagasse from theslurry to produce a miscella. As those skilled in the art willappreciate, the extent of mixing and/or agitation will vary dependingupon factors such as the size and concentration of the slurry orcombination of plant matter and solvents, the size and power of theequipment being utilized for the mixing and/or agitation. In certainembodiments of the processes disclosed herein, the plant matter and theorganic solvents (i.e., the at least one polar organic solvent and theat least one non-polar organic solvent) are allowed to remain in contactfor a certain period of time prior to removing the bagasse portion ofthe plant matter from the organic solvent portion that containssolubilized rubber and resin. In certain embodiments, this period oftime is 0.3-3 hours and in other embodiments 0.5-1.5 hours. In otherembodiments, a longer period of contact is allowed such as 1-8 hours ormore.

Removal of Bagasse from the Slurry

The following descriptions of the removal of bagasse from the slurryshould be understood to apply generally to the first, second and fourthembodiments of the processes disclosed herein which each of whichspecify removal of bagasse from a slurry to form a miscella. It shouldalso be understood to be applicable to certain embodiments of the thirdembodiment of processes disclosed herein, wherein further steps areutilized such as to prepare the solubilized guayule rubber solution froma slurry. As discussed above, according to the processes disclosedherein, a majority of the bagasse is initially removed from the slurryto produce a miscella. (Weight percentages of bagasse referred to hereinare based upon dry weights of bagasse (i.e., with any organic solventsand water having been removed). As discussed further below, the majorityof the bagasse that is initially removed is in certain embodiments is60-95 weight % of the bagasse contained within in the slurry, and inother embodiments 51-60 weight %, 60-80 weight %, 70-95 weight % or75-95 weight %. The total amount of bagasse present in the slurry may bedetermined by taking a representative sample of the slurry—taking careto ensure there is no settling of the bagasse within the slurry prior totaking the sample—and extracting the insoluble materials by repeatedrinsing and centrifuging. In other words, repeated rinsing andcentrifuging of sediment followed by repeated centrifuging of eachresulting supernatant to ensure complete removal of the insolublebagasse materials. Three or more rounds of rinsing and centrifuging maybe necessary. After condensing and drying of insoluble materials toremove organic solvents, the total weight of the insoluble materials canbe determined. The amount of bagasse present in the sample can becalculated and by extension the total weight of bagasse present in theentire slurry can be calculated.) The miscella contains a certain amountof bagasse (i.e., the portion not removed from the slurry), solubilizedrubber, solubilized resin, at least one polar organic solvent and atleast one non-polar organic solvent. In certain embodiments of theprocesses disclosed herein, 60-95 weight % of the bagasse, 60-80 weight%, 70-95 weight % or 75-95 weight % of the bagasse is removed from theslurry to form the miscella. In certain preferred embodiments of theprocesses disclosed herein, at least 70 weight % or at least 75 weight %of the bagasse is removed from the slurry to form the miscella.

This removal of the bagasse from the slurry take may place by utilizingvarious equipment and/or processes and/or chemicals. The bagasse portionthat is removed from the slurry is referred to herein as a first bagasseportion. In certain preferred embodiments of the processes disclosedherein, the removing of the bagasse from the slurry to produce amiscella is accomplished by using a centrifuge, optionally a decantercentrifuge. In other embodiments of the processes disclosed herein, theremoving of the bagasse from the slurry to produce a miscella isaccomplished using an extraction decanter or a screw press. In yet otherembodiments of the processes disclosed herein, the removing of thebagasse from the slurry to produce a miscella is accomplished using acounter-current extractor. While the following particular descriptionsof the bagasse from the slurry are explained with respect to the secondembodiment of the processes disclosed herein, it should be understoodthat each type of equipment described can also be utilized to removebagasse from the slurry in certain embodiments of the first embodimentof the processes disclosed herein. Furthermore, the detailed descriptionof the operation of a decanter centrifuge should be considered to beapplicable to certain embodiments of the fourth embodiment of theprocesses disclosed herein. In certain embodiments of the processesdisclosed herein, a portion or all of the first bagasse portion is fedback into the slurry so as to allow for transfer of additionalsolubilized rubber or resin that is associated with the solvent-wetbagasse into the liquid portion of the slurry (i.e., the miscella). Inother embodiments of the processes disclosed herein, none of the firstbagasse portion is fed back into the slurry. In certain embodiments ofthe processes disclosed herein, at least a portion of the miscella(containing solvents, rubber, resin and bagasse) that is produced fromthe slurry is fed back into the slurry. In other embodiments of theprocesses disclosed herein, none of the miscella is fed back into theslurry.

In certain embodiments, when a decanter centrifuge is utilized to removebagasse from the slurry, it is operated at a speed sufficient togenerate a g force of 500 to 3,500, preferably 1,000 to 3,000 or 1,000to 2,500. (As those skilled in the art will understand g force is ameasure of the amount of acceleration applied to a sample and is afunction of rotations per minute and rotation radius.) It is also withinthe scope of the processes described herein to utilize more than onecentrifuge to remove the majority of the bagasse from the slurry. Incertain embodiments of the processes described herein, the solidscontent of the miscella that is produced by removing bagasse from theslurry is 5-20 weight %, preferably 7-18 weight % (based upon the totalweight of the miscella), with solids being considered bagasse, rubberand resin. In certain embodiments according to the processes describedherein, the miscella contains 1-10 weight % rubber and 1-10 weight %resin; in other embodiments the miscella contains 3-7 weight % rubberand 3-9 weight % resin.

As previously discussed, in certain particular embodiments of the secondembodiment of the processes disclosed herein, the slurry is subjected toa centrifuging process in order to remove 70-95 weight % bagasse (basedon the total weight of bagasse in the slurry) to produce a miscella. Themiscella contains bagasse, solubilized rubber, solubilized resin, atleast one polar organic solvent and at least one non-polar organicsolvent. In certain embodiments, the slurry is subjected to acentrifuging process in order to remove at least 75 weight % bagasse; incertain such embodiments, 75-95 weight % of the bagasse. In certainembodiments, the centrifuge is a decanter centrifuge, and in certainsuch embodiments it is operated at a speed sufficient to generate500-3,500 g, preferably 1,000 to 3,000 g. It is also within the scope ofthe processes described herein to utilize more than one centrifuge toremove at least 70 weight % (e.g., 70-95 weight %) or at least 75 weight% (e.g., 75-95 weight %) bagasse from the slurry. In certain embodimentsof the processes described herein, the solids content of the miscellathat is produced by removing bagasse from the slurry is 5-20 weight %,preferably 7-18 weight % (based upon the total weight of the miscella),with solids being considered bagasse, resin and rubber. In certainembodiments of the processes disclosed herein, the miscella contains1-10 weight % rubber and 1-10 weight % resin or; in other embodiments ofthe processes described herein, the miscella contains 3-7 weight %rubber and 3-9 weight % resin.

As previously discussed, in certain particular embodiments of the secondembodiment of the processes disclosed herein the slurry is subjected toan extraction process in order to remove 60-95% by weight bagasse (basedon the total weight of bagasse present in the slurry), thereby producinga miscella. The extraction process may involve the use of an extractiondecanter. An extraction decanter can be a scroll-type centrifuge (oftenhorizontal) with a cylindrical conical solid-wall bowl. A scroll that isadapted to the bowl wall is located within the bowl and rotates therein.The suspension or slurry to be extracted is fed into the machine (oftenvia distributor slots in the scroll of the bowl). The slurry orsuspension then enters the counter-current extraction zone of the bowland flows to the conical end of the bowl via a separating disc againstthe flow of an extraction agent that is added (i.e., counter-currenteffect). The use of certain extraction decanters can allow for theaddition of additional solvent during the extraction process and may beoperated in a continuous or semi-continuous manner. Various types ofextraction decanters exist, including those that employ counter-currentextractions, scroll-type decanters and screen bowl type and solid bowltype. Preferably, the extraction decanter utilized is a counter-currentextractor. As used herein, the phrase extraction decanter should beunderstood to include various types of extraction decanters includingcounter-current extractors, scroll-type decanters, screen bowl type andsolid bowl typ. In certain embodiments according to the third embodimentof the processes disclosed herein, the slurry is subjected to anextraction process sufficient to remove at least 70 weight % bagasse. Incertain embodiments according to the third embodiment, the extractionprocess consists of an extraction decanter. An extraction decanter canbe operated at various settings, depending upon the size and parametersof the particular machine and the amount of bagasse that is to beremoved. It is also within the scope of the third embodiment of theprocesses described herein to utilize more than one extraction decanterto remove at least 70 weight % or at least 75 weight % bagasse from theslurry. In certain embodiments according to the third embodiment of theprocesses described herein, the solids content of the miscella thatexits the extraction decanter is 5-20 weight %, preferably 7-18 weight %(based upon the total weight of the miscella), with solids beingconsidered bagasse, resin and rubber. In certain embodiments accordingto the third embodiment of the processes described herein, the miscellathat exits the extraction decanter contains 1-10 weight % rubber and1-10 weight % resin. In other embodiments according to the thirdembodiment of the processes described herein, the miscella contains 3-7weight % rubber and 3-9 weight % resin. In certain embodiments accordingto the third embodiment of the processes disclosed herein where anextraction decanter is utilized and where it is desired to reduce theviscosity of the miscella, it will be possible to add part or all of theadditional solvent (i.e., polar organic solvent, non-polar organicsolvent or a combination thereof) directly to the extraction decanter soas to reduce the viscosity of the miscella exiting the extractiondecanter to less than 300 centipoise or less than 200 centipoise. It isalso specifically contemplated that the extraction process step (e.g.,using an extraction decanter) with its removal of a portion of thebagasse contained within the slurry may be used in combination with theaddition of additional solvent (i.e., polar organic solvent, non-polarorganic solvent or a combination thereof) so as to provide a modifiedmiscella that contains relatively less bagasse and, thus, has a solidscontent that is appropriate for processing via the next bagasse removalstep (which, in certain embodiments, entails the use of a disccentrifuge). It should be appreciated that when the solids content ofthe material entering the disc centrifuge is relatively lower (e.g., inthe range of 5-10 weight %), a relatively smaller disc centrifuge may beutilized.

As previously discussed, in certain particular embodiments of the secondembodiment of the processes disclosed herein, the slurry is subjected toa pressing process in order to remove at least 60% by weight bagasse(based on the total weight of bagasse present in the slurry), therebyproducing a miscella. The pressing process may involve the use of ascrew press. A screw press is a type of machine that contains a screwwithin a chamber the length of which is surrounded by cylindricalscreen-like material. The screw is caused to turn which causes thematerial within the chamber to press through the chamber and up againstthe screen. The shaft of the screw may be larger in diameter towards thefar end of the shaft so that the increasing diameter pushes the solidmaterial toward the screen whereby liquid is expelled through thescreen. Solid material is generally pushed along by the screw and may bepressed against the screen but does not pass through. As the screwcontinues to turn, a collection of solid material forms at the far endof the chamber. This solid material is often referred to as a presscake. At the far end of the chamber a plug or door is located (the plugor door is often called a cone). The cone is usually held shut by airpressure and the higher the air pressure, the harder the screw must pushagainst the press cake to open and the more liquid that is expelled fromthe press cake. Most screw presses can be operated in a continuousfashion. In certain embodiments of the processes disclosed herein, theslurry is subjected to a pressing process sufficient to remove at least70 weight % bagasse. In certain embodiments, the pressing process isaccomplished by a screw press. In embodiments where a screw press isutilized, it is can be operated at various conditions depending upon thesize and operating parameters of the particular screw press utilized.Various commercially available screw presses exist, including, but notlimited to, those sold by Vincent Corporation (Tampa, Fla.).

In certain embodiments of the processes disclosed herein where a screwpress is utilized it is operated at an rpm setting of 20-100 rpm, and ata back pressure of 5-15 psi (preferably 5-10 psi). It is also within thescope of the processes described herein to utilize more than one screwpress or pass the bagasse through the screw press more than once (withaddition of additional co-solvent to the bagasse press cake prior to anysecond pressing) to remove at least 70 weight % or at least 75 weight %bagasse from the slurry. In certain embodiments of the processesdescribed herein, the solids content of the miscella that exits thepress is 5-20 weight %, preferably 5-10 weight % (based upon the totalweight of the miscella), with solids being considered bagasse, resin andrubber. In certain embodiments of the processes described herein, themiscella (liquor) that exits the press contains 1-10 weight % rubber and1-10 weight % resin; in other embodiments, the miscella contains 3-7weight % rubber and 3-9 weight % resin.

In certain embodiments of the processes disclosed herein, the removalbagasse from the slurry to produce a miscella is achieved by the use ofa counter-current extractor. In certain embodiments, the bagasse removedby the counter-current extractor comprises 60-95% by weight of thebagasse that is contained within the slurry; in other embodiments 70-95%or even 75-95%. In certain embodiments utilizing the counter-currentextractor, the bagasse and solvents mixture (i.e., the slurry) is mixedwithin a separate extractor for a period of time prior to use of thecounter-current extractor, allowing for additional time for the solventto contact the plant matter and solubilize the rubber and resinscontained within the broken cells of the plant matter. In otherembodiments, the bagasse and solvents mixture (i.e., the slurry) is notpre-mixed prior to being added to the counter-current extractor or isonly pre-mixed just prior to being added to the counter-currentextractor. A counter-current extractor works by the general principle ofcirculating or moving solids in one direction, while circulating ormoving liquid (e.g., solvents) in the opposite direction, therebyincreasing the amount of contact between solids and liquid. Variousparticular configurations of counter-current extractors are availableand suitable for use in the processes disclosed herein.

In certain embodiments where a counter-current extractor is utilized,the plant matter that is mixed with the solvents to form the slurry isallowed to remain in contact with the solvents for a sufficient periodof time to allow solubilization of the rubber and resin that iscontained within the broken plant cells of the plant matter, prior toremoving the majority of the bagasse from the counter-current extractor.In certain such embodiments, the plant matter is allowed to remain incontact with the solvents for 0.3-3 hours prior to removing the majorityof the bagasse from the counter-current extractor; in other embodiments0.5 hours-1.5 hours. It should be understood that the plant matter maybe allowed to remain in contact with the solvents for longer period oftime such as 1-8 hours or 3-8 hours prior to removing the majority ofbagasse from the counter-current extractor. The contact periods of timereferred to include both the (average) time that the plant matter is incontact with the solvents in the counter-current extractor, as well asany time that the plant matter is in contact with the solvents in theseparate extractor, if such separate extractor is utilized.

In certain embodiments where a counter-current extractor is utilized,the counter-current extractor is configured such that it containsmultiple levels or stages with each level or stage containing bagassethat has been subjected to the solvents for varying and increasingamounts of time. Within these stages, the bagasse is moved through thecounter-current extractor by a conveyor belt, screw or another type ofconveying apparatus. At what can be considered the final level or stagewhich is where the bagasse has been in contact with the solvent for thelongest period of time, the bagasse is removed from the counter-currentextractor (such as by the use of a screw, a conveyor belt or anothertype of conveying apparatus). In certain embodiments, the bagasse thatis being removed from the counter-current extractor is subjected torinsing with fresh solvent (i.e., the mixture of non-polar organicsolvent and polar organic solvent) in order to remove at least part ofthe rubber that may be solubilized but is associated with thesolvent-wet bagasse.

In certain embodiments where a counter-current extractor is utilized,the bagasse that is removed from the counter-current extractor containsboth bagasse and solvent mixture in relative amounts of 40-80% by weightsolvent; in other embodiments, the bagasse that is removed contains40-60% by weight solvent or 40-50% by weight solvent. In certainembodiments where a counter-current extractor is utilized, the bagassethat is removed from the counter-current extractor is pressed orsqueezed to remove additional solvent. This squeezing or pressing may beemployed by one or more methods including, but not limited to, a screwpress, tray drier, extrusion, devolatilization, etc.

Adding Additional Organic Solvents

The following discussion should be understood as generally applicable tothe first and second embodiments of the processes disclosed herein.Additionally, in may be useful in certain embodiments of the third andfourth embodiments of the processes disclosed herein to utilizeadditional organic solvents, and, thus, the discussion may also beconsidered applicable to those embodiments. As previously discussed, incertain embodiments of the processes disclosed herein, additional polarorganic solvent, non-polar organic solvent or a combination thereof(each of which may be the same or different than the solvents present inthe slurry) is added to the miscella to form a reduced viscositymiscella. The reduced viscosity miscella contains bagasse, solubilizedrubber and resin as well as organic solvents. In certain preferredembodiments, any additional organic solvents added are the same as thosecontained within the slurry in order to simplify the process. The amountof any additional polar organic solvent that is added is less than theamount that causes the rubber contained within the reduced viscositymiscella to coagulate as the rubber should remain solubilized within thereduced viscosity miscella. As those skilled in the art will appreciate,the particular amount of any additional solvent(s) added will dependupon the volume of the miscella and the relative amounts of polar andnon-polar organic solvents contained within the miscella as well as theparticular subsequent processing to be performed upon the miscella toremove additional bagasse. In certain embodiments of the processesdisclosed herein, the amount of additional solvent(s) added is an amountsufficient to produce a reduced viscosity miscella with a viscosity ofless than 300 centipoise (e.g., 10-300 centipoise) and in otherembodiments less than 200 centipoise (e.g., 10-200 centipoise). Incertain embodiments, the step of adding additional polar organicsolvent, additional non-polar organic solvent or a combination thereofis performed within the previous bagasse removal step and the viscosityof the miscella is such that it does not require further reduction. Thegeneral purpose behind reducing the viscosity of the miscella is to makeit easier to remove smaller bagasse (e.g., fine bagasse finer than 105microns and fine bagasse larger than 45 microns) in the subsequent stepsof the process. As those skilled in the art will understand, the amountto which the viscosity of the reduced viscosity miscella is reduced (andaccordingly, the amount of any additional organic solvent(s) added) willto a large extent be dictated by the parameters of the remaining stepsof the process, including particularly the speed and/or number of stepsby which smaller bagasse are removed to ultimately produce thecoagulated rubber and solid purified rubber therefrom.

In certain embodiments of the processes described herein, the solidscontent of the reduced viscosity miscella or of the miscella/liquidmaterial entering the next bagasse removal process is 2-18 weight %,preferably 5-15 weight % (based upon the total weight of the reducedviscosity miscella or of the miscella/liquid material), with solidsincluding bagasse, rubber and resin. In certain embodiments according tothe first embodiment of the processes described herein, the reducedviscosity miscella (or the miscella) contains 0.5-7 weight % rubber and0.5-8 weight % resin (based upon the total weight of the reducedviscosity miscella or the miscella).

As previously discussed, in certain embodiments of the processesdisclosed herein, additional polar organic solvent, non-polar organicsolvent or a combination thereof (each of which may be the same ordifferent than the organic solvents present in the slurry) is added tothe miscella to form a reduced viscosity miscella with a viscosity lowerthan 200 centipoise (e.g., 10-200 centipoise). In other embodiments,additional polar organic solvent, non-polar organic solvent or acombination thereof is added to the miscella to form a reduced viscositymiscella with a viscosity lower than 300 centipoise (e.g., 10-300centipoise). One or more than one organic solvent may be added. One ormore than one polar organic solvent may be added. One or more than onenon-polar organic solvent may be added. The reduced viscosity miscellacontains bagasse, solubilized rubber and resin as well as organicsolvents. In certain preferred embodiments, additional polar organicsolvent is added to the miscella to form the reduced viscosity miscella.In certain preferred embodiments, any additional polar organic solventis added that is the same as the at least one polar organic solventcontained within the slurry in order to simplify the process. The amountof any additional polar organic solvent that is added is less than theamount that causes the rubber contained within the reduced viscositymiscella to coagulate as the rubber should remain solubilized within thereduced viscosity miscella. As those skilled in the art will appreciate,the particular amount of additional organic solvent(s) added will dependupon the volume of the miscella and the relative amounts of polar andnon-polar organic solvents contained within the miscella. The generalpurpose behind reducing the viscosity of the miscella is to make iteasier to remove smaller bagasse (e.g., fine bagasse finer than 105microns and fine bagasse larger than 45 microns) in the subsequent stepsof the process. As those skilled in the art will understand, the amountto which the viscosity of the reduced viscosity miscella is reduced (andaccordingly, the amount of additional organic solvent(s) added) will toa large extent be dictated by the parameters of the remaining steps ofthe process, including particularly the speed and/or number of steps bywhich smaller bagasse are removed to ultimately produce the coagulatedrubber and solid purified rubber therefrom. In certain embodimentsaccording to the second embodiment of the processes described herein,the solids content of the reduced viscosity miscella or of the liquidmaterial entering the next bagasse removal process is 2-18 weight %,preferably 5-15 weight % (based upon the total weight of the reducedviscosity miscella), with solids including bagasse, rubber and resin. Incertain embodiments according to the second embodiment of the processesdescribed herein, the reduced viscosity miscella contains 0.5-7 weight %rubber and 0.5-8 weight % resin (based upon the total weight of thereduced viscosity miscella).

Second Removal of Bagasse

As should be clear from the previous discussion of the processesdisclosed herein, after the miscella is produced by removing a majorityof the bagasse from the slurry, additional bagasse remains within themiscella, a portion of which must be removed in order to produce acommercially acceptable final rubber product. As previously discussed,in the first and third embodiments of the processes disclosed herein,80-95 weight % bagasse (based on the total weight of bagasse present inthe reduced viscosity miscella or the miscella from which a majority ofbagasse has been removed) is removed from the reduced viscosity miscellaor from the miscella to form a purified miscella. A majority of thebagasse that is removed to form the purified miscella has a particlesize less than 105 microns. (In other words, at least 50% by weight ofthe bagasse that is removed has a particle size less than 105 micronsand in certain embodiments at least 90% or 95% by weight of the bagassethat is removed has a particle size less than 105 microns. The particlesize range of the bagasse that is removed can be determined by dryingthe bagasse to remove organic solvents and then subjecting the driedmass to particle size analysis such as by sieve analysis. Variousmethods for particle size analysis are well known to those skilled inthe art.) The purified miscella contains solubilized rubber and resin aswell as organic solvents. In certain embodiments of the processesdisclosed herein, at least 85 weight % (e.g., 85-95 weight %) or atleast 90 weight % (e.g., 90-95 weight %) bagasse is removed to form theto form a purified miscella. In certain preferred embodiments accordingto the first and third embodiments of the processes disclosed herein,the removing of additional bagasse to produce the further purifiedmiscella is accomplished by using a centrifuge, optionally a diskcentrifuge. In certain embodiments, when a disk centrifuge is utilized,it is operated at a speed sufficient to generate a g force of 4,000 to12,000, preferably 7,000 to 10,000. It is also within the scope ofcertain embodiments of the first and third embodiments of the processesdescribed herein to utilize more than one centrifuge or more than onetreatment method to remove the additional bagasse to produce thepurified miscella. In certain embodiments of the processes describedherein, the solids content of the purified miscella is 2-16 weight %,preferably 3-12 weight % (based upon the total weight of the purifiedmiscella), solids including rubber, resin and bagasse. In certainembodiments according to the processes described herein, the purifiedmiscella contains 0.5-7 weight % rubber and 0.5-8 weight % resin (basedupon the total weight of the purified miscella).

Further Purification of the Purified Miscella

As previously discussed, optionally certain embodiments of the processesdisclosed herein, the purified miscella is treated to remove additionalbagasse thereby producing a clarified rubber solution that contains0.01-1% bagasse (based on the total weight of bagasse present in theslurry). In certain such embodiments, 0.01-0.5% bagasse or even0.01-0.1% bagasse (based on the total weight of bagasse present in theslurry) remains in the clarified rubber solution. 90-99% (by weight) ofthe additional bagasse that is removed (from the purified miscella) hasa particle size greater than 45 microns and in other embodiments, 95-99%by weight of the additional bagasse that is removed has a particle sizegreater than 45 microns. The clarified rubber solution containssolubilized rubber and solubilized resin (from the plant matter) as wellas polar and non-polar organic solvent. In certain preferredembodiments, the removing of additional bagasse from the purifiedmiscella is accomplished by filtering, optionally by the use of ascreen-bar element type-filter containing openings of 45 microns orless, continuously scraped by a rotating blade. Screen-bar element typefilters are characterized by a screen filter with opening of a specifiedsize through which fluid is passed. Solids larger than the openings arecaught by the screen filter and removed from the screen filter byscraping such as by a rotating blade. The solids can then fall to thebottom of the filter apparatus where they can be collected and/ordischarged periodically. Other processes, including, but not limited toother filtering methods, may be used to remove additional bagasse fromthe purified miscella to produce a clarified rubber solution thatcontains 0.01-1% bagasse (based on the total weight of bagasse presentin the slurry). It is also within the scope of the processes describedherein to utilize more than one filter or more than one treatment methodto remove the additional bagasse thereby producing a clarified rubbersolution that contains 0.01-1% bagasse (based on the total weight ofbagasse present in the slurry).

Organic Solvents

In any of the embodiments of the processes disclosed herein, the organicsolvents contained within the slurry (or within the solubilized guayulerubber solution of the third embodiment) and any additional organicsolvents (polar organic solvent, non-polar organic solvent, or acombination thereof) added to the miscella to form a reduced viscositymiscella or elsewhere in the process may be the same or different (i.e.,overall one non-polar organic solvent may be utilized and overall onepolar organic solvent may be utilized, or alternatively more than one ofeach maybe be utilized.). Preferably, all non-polar organic solventutilized within the process are the same and all polar organic solventutilized within the process are the same.

In any of the foregoing embodiments of the processes disclosed herein,the at least one polar organic solvent of the slurry (or within thesolubilized guayule rubber solution of the third embodiment) and anyadditional polar organic solvent added to the miscella to form a reducedviscosity miscella or added elsewhere in the process may be selectedfrom the group consisting of alcohols having 1 to 8 carbon atoms (e.g.,ethanol, isopropanol, ethanol and the like); ethers and esters havingfrom 2 to 8 carbon atoms; cyclic ethers having from 4 to 8 carbon atoms;and ketones having from 3 to 8 carbon atoms (e.g., acetone, methyl ethylketone and the like); and combinations thereof. In certain preferredembodiments of the processes disclosed herein, the at least onenon-polar organic solvent and any additional non-polar organic solventare each hexane or cyclohexane with the at least one polar organicsolvent and any additional polar organic solvent optionally beingacetone. Other polar organic solvents (individually or in combination)may be used in embodiments of the processes disclosed herein as long asthe polar organic solvent preferentially solvates a portion ofnon-rubber extractables (e.g., resins) and acts (at a certainconcentration) to coagulate natural rubber. In any of the embodiments ofthe processes disclosed herein, mixtures of two or more polar organicsolvents may be utilized.

In any of the foregoing embodiments of the processes described herein,the at least one non-polar organic solvent that is contained within theslurry and any additional non-polar organic solvent added to themiscella to form a reduced viscosity miscella or elsewhere in theprocess may be selected from the group consisting of alkanes having from4 to 9 carbon atoms (e.g., pentane, hexane, heptanes, nonane and thelike); cycloalkanes and alkyl cycloalkanes having from 5 to 10 carbonatoms (e.g., cyclohexane, cyclopentane and the like); aromatics andalkyl substituted aromatics having from 6 to 12 carbon atoms (e.g.,benzene, toluene, xylene and the like); and combinations thereof. Incertain preferred embodiments according to the first, second and thirdembodiments of the processes disclosed herein, the at least one polarorganic solvent of the slurry and any additional polar organic solventare each acetone, and the at least one non-polar organic solvent of theslurry and any additional non-polar organic solvent are optionallyhexane or cyclohexane. Other non-polar organic solvents (individually orin combination) may be used in embodiments of the processes disclosedherein as long as the non-polar organic solvent preferentially solvatesnatural rubber. In any of the embodiments of the processes disclosedherein, mixtures of two or more non-polar organic solvents may beutilized.

As previously discussed, in certain embodiments of the processesdescribed herein, the relative amount of at least one non-polar organicsolvent and at least one polar organic solvent contained within theslurry is 50-90% by weight and 10-50% by weight, respectively, basedupon the total amount of organic solvent. In certain preferredembodiments, the amount of the at least one non-polar organic solvent is60-85% by weight and the amount of the at least one polar organicsolvent is 15-40% by weight. In certain embodiments of the processesdisclosed herein, it is advantageous to control or adjust the viscosityof the combined organic solvent mixture (i.e., the at least onenon-polar organic solvent and the at least one polar organic solvent) to10-1000 centipoise, particularly for certain portions of the processsuch as the slurry portion where rubber and resin are being solubilizedfrom the ruptured cells of the plant. In certain such embodiments, theviscosity of the combined organic solvent mixture is controlled oradjusted to 35-800 centipoise. Relatively higher viscosities within theforegoing ranges will be useful for a portion of the process whererubber and resin solubilization from the ruptured cells of the plant isoccurring so as to maximize solubilization and minimize settling ofbagasse particles. Conversely, a relatively lower viscosity within theforegoing ranges will be useful for a portion of the process whererubber and resin have already been solubilized, but the bagasse is beingwashed to ensure that solubilized rubber and resin are retained with theliquid/solvent instead of with the solvent-wet bagasse.

Miscellaneous

In various embodiments according to the processes disclosed herein, oneor more antioxidants may optionally be utilized along with the plantmatter, the slurry or elsewhere in the process of removing rubber fromthe plant matter. In preferred embodiments of the processes disclosedherein, one or more antioxidant are added to the clarified rubbersolution before the relative amount of polar organic solvent as comparedto non-polar organic solvent is increased. However, in other embodimentsof the processes disclosed herein, one or more antioxidants may be addedat one or more other points during the process. Preferably, when one ormore antioxidants are added, they are added after removal of the atleast 80%, at least 85% or at least 90% bagasse from the reducedviscosity miscella. Alternatively, in certain embodiments of theprocesses disclosed herein, one or more antioxidants may be added to theplant matter prior to its incorporation into the slurry. Suitablecompounds for use as the one or more antioxidants in the processesdisclosed herein include, but are not limited to,2,6-di-t-butyl-4-methylphenol (also known as 2,6-di-t-butyl-p-cresol);N-(1,3-dimethylbutyl)-N′-phenyl-1,4-benzenediamine;octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate (commerciallyavailable as Irganox® 1076); 4,6-bis (octylthiomethyl)-o-cresol(commercially available as Irganox® 1520), monohydric hindered phenolssuch as 6-t-butyl-2,4-xylenol, styrenated phenols, butylatedoctylphenols; bisphenols, for example4,4′-butylidenebis(6-t-butyl-m-cresol), polybutylated bisphenol A,hindered hydroquinones such as 2,4-di-t-amylhydroquinone; polyphenols,such as butylated p-cresol-dicyclopentadiene copolymer; phenolicsulfides such as 4,4′-thiobis(6-t-butyl-3-methyl-phenol),alkylated-arylated bisphenol phosphites such astris(nonylphenyl)phosphite, triazinetriones such as alkylatedhydroxycinnamate triester of tris(2-hydroxyethyl)-triazinetrione,tris(alkyhydroxybenzyl)-triazinetrione; pentaerythritol esters such astetrakis(methylene-3,5-di-t-butyl-4-hydroxyhydrocinnamate)-methane;substituted diphenylamines such as octylated diphenylamines,p-(p-touenesulfonamido)-di-phenylamine, nonylated diphenylamine,diisobutylene-diphenylamine reaction products; dihydroquinolines such as6-dodecyl-1,2-dihydro-2,2,4-trimethylquinoline; dihydroquinolinepolymers such as 1,2-dihydro-2,2,4-trimethylquinoline polymer;mercaptobenz-imidazoles such as 2-mercaptobenzimidazole; metaldithiocarbamates such as nickel dibutyldithiocarbamate, nickeldiisobutyldithiocarbamate, nickel dimethyldithiocarbamate;ketone/aldehyde-arylamine reaction products such asaniline-butyraldehyde condensation products, diarylamine-ketone-aldehydereaction products; and substituted p-phenylenediamines such asdi-b-naphthyl-p-phenylenephenylenediamine andN-phenyl-N′-cyclohexyl-p-phenylenediamine. The total amount of theantioxidant employed in those embodiments of the processes disclosedthat utilize at least one antioxidant herein may be in the range of 0.2%to 2% by weight of the purified solid rubber ultimately produced by theprocess (based upon the weight of the purified solid rubber containingless than 0.5 weight % solvent).

As previously discussed, the relative amount of polar organic solvent ascompared to non-polar organic solvent within the clarified rubbersolution is increased so as to coagulate the rubber that is solubilizedwithin the clarified rubber solution. In certain embodiments, the amountof polar organic solvent is increased by adding additional polar organicsolvent. In other embodiments, the relative amount of polar organicsolvent is increased by removing non-polar organic solvent. The relativeamount of polar organic solvent is increased to an extent that causesthe rubber contained within the clarified rubber solution to begin tocoagulate. The particular amount of additional polar organic solventthat is added and/or the particular amount of non-polar organic solventthat is removed will depend upon the volume of the miscella and therelative amounts of polar and non-polar organic solvents containedwithin the miscella and upon the amount of rubber coagulation desired.Higher molecular weight rubber (which is generally more desirable interms of a final product) will coagulate first. In certain embodimentsaccording to the first, second and third embodiments, coagulation iscontrolled so that higher molecular weight rubber (preferably rubberwith a molecular weight of at least 800,000 (e.g., 800,000-1,5,00,000),even more preferably at least 1,000,000 (e.g., 1,000,000-1,500,000))coagulates and lower molecular weight rubber remains in solution. Themolecular weights of rubber that are referred to herein are determinedby GPC, utilizing a polystyrene standard.

In certain embodiments of the processes disclosed herein, it may behelpful to allow for some amount of settling time so that the fractioncontaining higher molecular weight rubber can separate from the lighterfraction containing lower molecular weight rubber and also resin. Incertain embodiments of the processes disclosed herein, a fractionator(optionally cone-shaped) may be utilized to assist in the separationwhereby the heavier, higher molecular weight rubber fraction settles atthe bottom of the fractionators and can be removed (such as by pumping)from the bottom. In certain embodiments of the processes disclosedherein, the removal of the higher molecular weight rubber fraction iscontinuous so as to maintain a constant or relatively constant phaseinterface within the fractionator. The upper phase (containing lowermolecular weight rubber and resin) can be separated and may be recycledor re-used in various ways. In certain embodiments, the relative amountof polar organic solvent as compared to non-polar organic solvent can beincreased by both adding additional polar organic solvent and removingnon-polar organic solvent. In certain embodiments, one or more than oneadditional polar organic solvent can be added to the clarified rubbersolution in a total amount so as to coagulate the rubber solubilizedtherein. In preferred embodiments, when additional polar organic solventis added, it is the same polar organic solvent as is contained withinthe slurry. In other embodiments according to the first, second andthird embodiments, when additional polar organic solvent is added, itmay be a different polar organic solvent than is contained within theslurry.

As previously discussed, according to the processes disclosed herein,solid purified rubber can be produced from the coagulated rubber thatcoagulates in the clarified rubber solution. Various processes can beutilized for isolating the solid purified rubber. These processesgenerally comprise removal of solvent (primarily non-polar organicsolvent but also some polar organic solvent) associated with thecoagulated rubber. Residual solvent can be removed from the coagulatedrubber by evaporating the solvent such as with the application of heatand/or vacuum. In certain embodiments of the processes disclosed herein,the residual solvent is removed in one or multiple phases (two, three,four, five or more) that include the use of both heat and vacuum. Incertain embodiments, heat that is applied preferably raises thetemperature of the coagulated rubber to above the boiling point of theresidual organic solvents associated with the coagulated rubber. Incertain embodiments, this temperature is 40° C. to 100° C. in order tofacilitate the removal of solvent. In certain embodiments, the pressureis reduced to 3-30 inches Hg (10-100 kPa) in order to facilitate theremoval of solvent. Solvent that is removed can be condensed andrecovered for further use. In preferred embodiments, the solid purifiedrubber that is produced has a molecular weight of at least 800,000(e.g., 800,000-1,500,000), even more preferably at least 1,000,000(e.g., 800,000-1,500,000), molecular weight being based upon apolystyrene standard. The amount of solvent that is removed from thecoagulated rubber will vary according to desired use and shipmentmethod. In certain embodiments, solid purified rubber can be collectedinto bales. In preferred embodiments, no more than 2 weight %,preferably no more than 1 weight % and even more preferably no more than0.8 weight % of volatile matter (based upon the total weight of thesolid purified rubber) remains within the solid purified rubber after ithas been subjected to one or more solvent removal steps. As previouslydiscussed, according to certain embodiments of the processes describedherein, when the solid purified rubber contains 0.8 weight % volatilematter, it will also contain 0.05-0.5 weight % dirt, 0.2-1.5 weight %ash and 0.1-4 weight % resin. (It should be understood that the solidpurified rubber produced according to the processes disclosed herein maycontain relatively more or less organic solvent, and that the 0.8 weight% volatile matter is provided as an exemplary content for purposes ofdetermining whether sufficient removal of dirt, ash and resin has beenachieved. In certain preferred embodiments, the solid purified rubbercontains 0.8 weight % or less volatile matter.

In certain embodiments of the processes described herein, the amount ofrubber that is removed from the slurry represents at least 95 weight %(e.g., 95-99 weight % or 95-98 weight %) of the rubber that is containedwithin the plant matter-containing slurry. Preferably, in suchembodiments, the plant matter is from guayule shrubs. In certain morepreferred embodiments of the processes described herein, the amount ofrubber that is removed from the slurry represents at least 96 weight %(e.g., 96-99 weight % or 96-99 weight %) of the rubber that is containedwithin the plant matter-containing slurry. In certain embodiments, theplant matter is from guayule shrubs. In preferred embodiments of theprocesses described herein, the amount of rubber that is removed fromthe slurry represents at least 98 weight % of the rubber that iscontained within the plant matter-containing slurry. Preferably, in suchembodiments, the plant matter is from guayule shrubs. Total rubberpresent in the plant matter-containing slurry can be determinedfollowing a similar method as to that used to determine total bagassepresent in the slurry, as discussed above, except focusing upon thesupernatants obtained from repeated centrifuging and rinsing. After allbagasse has been removed from the slurry sample (using the repeatedcentrifuging and rinsing procedure described previously), thesupernatant portions are collected together and the rubber within iscoagulated by adding additional polar solvent (the resin will remainsolubilized). Polar solvent should be added beyond the point at whichcoagulation begins to ensure coagulation of lower molecular weightrubber as well as higher molecular weight rubber. The coagulated rubbercan then be filtered away from the solvents, rinsed with severaladditional pure polar solvent fractions (the rinse being added to theresin-containing solvent portion). After drying (to remove any remainingsolvent), the rubber is weighed and the total amount of rubber in theoriginal plant matter-containing slurry can be calculated. Total resinpresent in the plant matter-containing slurry can be determined bydrying the solvent left behind after the rubber coagulates (adding inall additional polar solvent rinses used to rinse the coagulatedrubber).

Temperature

As previously discussed, multiple aspects of the processes herein areconducted at a temperature or temperatures of 10-80° C. and differentaspects of the process may be conducted at the same temperature or atdifferent temperatures) and a pressure of 35-1000 kPa. In certainembodiments according to the processes disclosed herein, multipleaspects of the process are conducted at a temperature or temperatures of10-50° C. (preferably those aspects of the process denoted as (a)-(e) invarious embodiments herein and/or meeting the description of being priorto the stage where organic solvent is removed from coagulated rubber).As those skilled in the art will understand, the particular temperatureor temperatures at which the individual aspects of the processes areconducted may vary depending upon the identity of the at least polarorganic solvent and at least one non-polar organic solvent utilized.However, it is intended that those aspects of the processes disclosedherein that are directed to removing bagasse from the slurry to producea miscella; adding additional polar organic solvent to produce a reducedviscosity miscella; removing 80-95 weight % bagasse from the reducedviscosity miscella (or the miscella) to form a purified miscella; andoptionally treating the purified miscella to remove additional bagassethereby producing a clarified rubber solution containing 0.01-1% byweight bagasse will be operated at a temperature or temperatures belowthe boiling point of the mixture of at least one polar organic solventand at least one non-polar organic solvent utilized. Subsequent or lateraspects of the processes (i.e., increasing the relative amount of polarorganic solvent as compared to non-polar organic solvent within theclarified rubber solution so as to coagulate the rubber and producingsolid purified rubber from the coagulated rubber) are preferablyconducted at a temperature or temperatures above the boiling point ofthe at least one polar organic solvent and/or above the boiling point ofthe mixture of the at least one polar organic solvent and at least onenon-polar organic solvent.

Multiple steps within each of the first, second, third and fourthembodiments of the processes described herein are preferably conductedon a continuous basis. In certain embodiments of the first and secondembodiments of the processes described herein, (a)-(g) are conducted ona continuous basis.

EXAMPLES

The following examples are for purposes of illustration only and are notintended to limit the scope of the claims which are appended hereto.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the technology of this application belongs. While thepresent application has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the application, in its broaderaspects, is not limited to the specific details, the representativeembodiments, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicant's general inventive concept.

Example 1

A sample was prepared in order to simulate the removal of rubber from anon-Hevea rubber source. A champion bottle was used to prepare a samplethat was 500 mL in volume and consisted of 12.4% (w/w) insoluble fines(the insoluble fines were bagasse and dirt/soil from harvesting ofguayule shrub pellets), 4.8% (w/w) soluble rubber (obtained fromcoagulation of a natural rubber latex sourced from guayule shrubs) and1.6% (w/w) mixed soluble resin plus degraded rubber. The mixed solubleresin plus degraded rubber and the insoluble fines were obtained fromguayule shrub pellets using a co-solvent mix of 80 weight % hexane and20 weight % acetone. The pellets had been prepared about 1.5 yearsearlier from chopped guayule shrub and stored. Upon use the pelletscontained negligible, if any, moisture. The insoluble fines, solublerubber and mixed soluble resin plus degraded rubber were dissolved usinga co-solvent of acetone and hexane (the co-solvent contained 80 weight %hexane and 20 weight % acetone). The sample was shaken by hand and thenquickly poured into 15 mL centrifuge tubes (shaking by hand betweenpours).

In order to simulate the step of removing bagasse, spin tests wereconducted by placing the 15 mL centrifuge tubes into a Flottweg bottlecentrifuge using settings of 1000×g (Sample 1-A) and 3000×g. (Sample1-B) for the times indicated below in Table 1. A third treatment wasconducted by first using a setting of 1000×g for 5 minutes and thensubjecting the centrate from that test to a second spin treatment at3000×g (Sample 1-C). Upon completion of the spinning, test samples wereremoved and analyzed to determine the amount of compacting of the solidsand the % volume of sedimented material (results appear in Table 1).Thereafter, the centrate was decanted from the solids. Decanted centratewas analyzed after desolventization (to remove all or substantially allof the solvent and leave behind both soluble and insoluble solids). Thepercentage by weight of insoluble solids remaining could then becalculated and compared to the target of no more than 6% insolublesolids (results appear in Table 2). Thereafter, the solids from thebottom of the tube were analyzed to determine the relative amounts ofsoluble and insoluble solids contained therein (results appear in Table2).

TABLE 1 Centrifuge Time Sediment setting (minutes) volume (%) PackingSample 1-A 1000 × g 1 30 medium compact 2 30 medium compact 5 30 mediumcompact Sample 1-B 3000 × g 1 30 medium compact 2 30 medium compact 5 30medium compact

TABLE 2 Dry substance analysis Stage of testing % dissolved solids Feedsample (before centrifuging) 23.8 Feed sample (before centrifuging) 22.5Centrate from 1000 × g, 5 minutes 11.6 (7.0% soluble and 4.6% insoluble)Centrate from 3000 x g, 5 minutes 10.5 (7.1% soluble and 3.4% insoluble)

Example 2

In order to simulate the removal of rubber from a non-Hevea rubbersource, several batches of rubber solution with different % fines wereprepared as the feed material (the solutions were prepared from guayuleshrub pellets and co-solvent of 80/20 hexane/acetone that were subjectedto different treatments including screw press treatment). Sets ofexperiments were conducted with differing flow rates at 7000×g (lowsetting) and 12000×g (high setting) G-force. Centrate samples werecollected from each set of experiments after centrifuging using aWestfalia Model CTC1 disc centrifuge. This disc centrifuge contains abowl with 1 liter volume capacity and can hold up to 0.5 liters insolids. After centrifuging, solid rubber samples were coagulated fromthe centrate by adding additional acetone to the centrate until therubber coagulated (generally rubber coagulation will occur at about1.2:1 hexane/acetone weight ratio). The solvent was decanted from thecoagulated rubber and the wet rubber that remained was desolventized bydrying in a vacuum oven at 70° C. Ash and dirt concentrations within thedried rubber samples were analyzed using ASTM D1278-91. Results aresummarized in Table 3.

TABLE 3 % Fines in Feed Flow Rate % Ash in % Dirt in Highest w/w % v/v %Sample ID G Force (L/min) Rubber Rubber TSR Met 0.06 0.15 2688-131 70000.25 0.22 0.07 TSR-10 12000 0.25 0.17 0.15 TSR-20 0.42 1 2688-139 70000.5 0.53 0.16 TSR-20 1 0.67 0.16 TSR-20 1.5 0.69 0.09 TSR-20 12000 0.50.34 0.09 TSR-10 1 0.31 0.05 TSR-CV 1.5 0.47 0.16 TSR-20 0.58 1.42688-129 7000 1.25 0.73 — 12000 0.5 0.15 — 1.6 3.8 2688-137 7000 0.50.44 — 1 0.54 0.14 TSR-20 1.5 0.61 0.06 TSR-10 12000 0.5 0.24 0.04TSR-CV 1 0.56 0.07 TSR-10 1.5 0.60 0.13 TSR-20 5.31 12.6 2688-141 70000.5 0.61 0.16 TSR-20 1 0.86 0.22 TSR-50 1.5 1.34 0.26 TSR-50 12000 0.50.27 0.12 TSR-50 1 0.45 0.07 TSR-10 1.5 0.53 0.17 TSR-20 6.83 16.22688-143 7000 0.5 1.17 0.32 TSR-50 1 1.64 0.38 1.5 1.81 — 12000 0.5 0.720.08 TSR-10 1 1.32 0.14 TSR-50 1.5 1.20 0.05 TSR-50

From these experiments, it is shown that a high G-force centrifuge iscapable of separating feed materials with fines below about 13% (v/v) atflow rates of up to 1.5 L/minute to produce a final solid rubber thatgenerally meets ISO TSR-50 standards. (ISO has specified six differentgrades for natural rubber by which the rubber is technically specified.The grades are referred to as TSR (Technically Specified Rubber). TSR L(high quality and light colored rubber prepared from latex), TSR CV(viscosity-stabilized high quality latex rubber), TSR 5 (good qualitylatex rubber, darker than TSR L), TSR 10 and 20 (good quality gradesderived from field coagulum, suitable for general purpose uses), TSR 50(up to 0.50% weight dirt content. The specifications and characteristicsof TSR grades are summarized in Table 4.) With a lower flow rate of 0.5L/minute, the particular bench top centrifuge was still able to handlefeed material having fines of 16.2% (v/v) when operating at the high Gforce setting. For feed materials with fines of 12.6% (v/v) the flowrate needed to be limited to 1 L/minute in order for the final solidrubber to meet TSR-50 and have no more than 0.5 weight % dirt and nomore than 1.5 weight % ash.

TABLE 4 Grades TSR TSR TSR TSR TSR- Parameters CV L TSR 5 10 20 50 Dirt(max) % wt 0.05 0.05 0.05 0.10 0.20 0.50 Ash (max) % wt 0.60 0.60 0.500.75 1.00 1.50 Nitrogen (max) % wt 0.60 0.60 0.50 0.60 0.60 0.60Volatile matter (max) % 0.80 0.80 0.80 0.80 0.80 0.80 wt Initial wallaceplasticity 30 30 30 30 30 Po (Min) Plasticity Retention 60 60 60 50 4030 Index PRI (Min) Color Lovibond Scale 6 (individual value, max) Mooneyviscosity (ML, 60 ± 5 1 + 4, 100° C.)

Example 3 Preparation of Pellets from Guayule Shrubs

Guayule shrubs that were approximately 7 years old were cut above theroot during the winter. The cut shrubs were left in the field with theintention of drying. However, during harvest, heavy rains occurred thatslowed the rate of drying. Because of the rain, no leaf removaloperation was performed, but based upon the fact that spring regrowth ofleaves had not yet begun, the weight percentage of the leaves wasestimated to be less than 20% (on a dry basis). Approximately 3 weeksafter harvesting had begun, the cut shrubs were subjected to coarsechopping to a maximum diameter of about ⅜″ (0.95 cm) using ashredder/chopper. The chopped shrub pieces were placed in coveredcontainers and transported to a pelletizing location. Upon receipt atthe pelletizing location, the containers were immediately opened. Fourdays after receipt of the chopped material, processing was begun(processing began approximately 4 weeks after harvest). The entireshipment of chopped guayule material was first hammer milled using a ½″screen. The resulting material was then passed over a 20 mesh vibratingscreen to remove fines. The oversized material that remained on thescreen was pelletized using a ¼″ die. The final moisture content of thepellets was found to be 16 weight % and upon analysis (using soxhletextraction with acetone/pentane azeotrope) the pellets were found tocontain 9% resin and 4.4% rubber. The pellets were shipped in a sealed55 gallon drum container which upon receipt was opened, nitrogen purgedand re-sealed.

Example 4 Use of Screw Press to Remove Bagasse

A 35 pound sample of slurry was utilized. The slurry was prepared bycombining pellets made from guayule plant matter (as described inExample 3, above), hexane and acetone. The pellets were analyzed byscrew press approximately 2 months after pelletization. (After receiptfrom the pelletizing location, the pellets were stored in a 55 gallonplastic drum which had been closed, nitrogen purged and sealed.) Thetarget composition of the slurry was 18 weight % bagasse, 57 weight %hexane, 14 weight % acetone, 5 weight % rubber and 6 weight % resin (thebagasse, rubber and resin were all from the pellets). A screw press fromVincent Corporation (model number CP-4) was utilized to separate aquantity of the bagasse from the slurry and various combinations ofdischarge pressure and screw speed were evaluated. Three differentscreens with varying shape and size mesh were also evaluated. Twoscreens contained slot-shaped openings (one with openings 0.017″ (0.043cm) wide and the other with 0.011″ (0.028 cm) wide openings). The thirdscreen had circular openings with a diameter of 0.023″ (0.058 cm). Asprovided in Table 5 below, various batches of the slurry were processedthrough the screw pressing, using the combinations of screen press speedand back pressure indicated. Batches 1-3 used the screen with 0.017″slot-shaped openings, batches 4-12 used the screen with 0.011″slot-shaped openings and batches 13-17 used the screen with 0.023″circular openings. The liquid (liquor) containing solubilized solvents,solubilized rubber, solubilized resins and some amount of bagasse wascollected from the screw press outlet. The bagasse that had accumulatedinto a press cake was separately collected.

For most of the batches, samples were taken from the feed slurry (alsocalled the original slurry), the press liquor and the bagasse presscake. The weight percentages of fines and rubber in samples of pressliquor were determined by subjecting samples of the press liquor tocentrifuging and then the supernatant from the centrifuging tocoagulation (by addition of acetone) The weight percent solvent in thebagasse press cake samples was determined by weighing the cake samplebefore and after drying overnight in a vacuum oven at 70° C. The solidsseparation efficiency was determined according to the followingequation: solids separation efficiency=((% biomass in originalslurry)-(%fines in press liquor))/(% biomass+water in original slurry).The liquid separation efficiency was determined according to thefollowing equation: liquid separation efficiency=((% liquid in originalslurry)−(% liquid in press cake))/(% liquid phase in original slurry).(With the liquid phase including acetone, hexane and dissolved rubberand resin.) While the percent solids in the feed slurry is known toaffect the separation efficiency of the screw press, that factor wasminimized in the batches analyzed because % biomass+water in theoriginal slurry (feed slurry) were maintained at around 22%.

TABLE 5 Analysis of liquor Analysis of bagasse cake Press Back SolidsSolvent Liquid speed pressure % % fines % Separation Solvent in cakeseparation Batch # (rpm) (psi/Pa) fines adjusted* rubber efficiency incake (adj)* efficiency 1 100 10 8.1 8.1 — 0.58 — — — 2 60 10 15.2 14.05.5 0.37 — — — 3 45 10 16.8 16.8 6.2 0.16 — — — 4 45 10 8.7 11.2 4.10.50 48 52.5 0.32 5 100 15 — — 4.4 — 28.5 31.2 0.60 6 100 5 6.7 8.3 4.70.61 40 41.7 0.47 7 60 5 11.5 12.9 4.1 0.39 48.8 49.9 0.37 8 150 5 11.514.6 3.8 0.31 35.8 49.6 0.37 9 150 10 8.5 11.2 4.0 0.55 39.3 48.5 0.3610 150 10 — — — — — 50.2 — 11 140 10 11.1 13.9 5.5 0.34 38.6 44.2 0.4412 160 10 6.8 8.2 2.5 0.53 43.2 51.2 0.38 13 100 10 11.2 16.2 5.1 0.4843.2 50.1 0.27 14 60 10 9.6 13.5 4.6 0.52 41.2 49.0 0.32 15 40 10 8.912.3 4.3 0.55 42.0 50.2 0.31 16 25 10 7.5 9.5 4.4 0.55 43.8 46.2 0.41 1725 5 6.8 8.7 4.6 0.60 43.6 50.8 0.35 *The adjusted numbers take intoaccount solvent loss that occurred from evaporation due to the fact thatthe machinery was not sealed (by adding back in the lost solvent).Solvent loss was calculated as slurry weight minus wet cake weight minusclarified liquid weight.

As can be seen from a review of the data in Table 5, the screw press wasable to achieve greater than 50% solids separation efficiency for eachtype of screen operated under at least one set of conditions.

Example 5 Use of Screw Press to Remove Bagasse

Four gallon quantities of slurry were prepared by combining wet guayulepellets with acetone, hexane and dry rubber. Prior to preparation of theslurry, the wet guayule pellets were found to contain 11.74 weight %moisture, 6.67 weight % rubber (dry weight basis) and 8.44 weight %resin (dry weight basis). The dry rubber was obtained by coagulating asample of Yulex guayule latex, with 1 phr Santoflex 134 antioxidantadded prior to coagulation). 5.56 pounds of wet pellets were mixed with381.47 grams of dry rubber in 14.9 pounds hexane and 3.72 pounds acetoneto produce the slurry. The feed slurry contained about 19% biomass andthe liquid phase of the slurry (about 81 weight %) contained about 6weight % rubber, 2 weight % resin and 92 weight % organic solvent.Samples of the slurry were subjected to two types of screw pressevaluation. The first utilized a screw press/french oil millmanufactured by the French Oil Mill Machinery Company and the secondutilized a screw press manufactured by Vincent Corporation. This screwpress was a Vincent Corporation screw extruder (model no. CP-4).

The liquid (liquor) containing solubilized solvents, solubilized rubber,solubilized resins and some amount of bagasse (fines) was collected fromthe screw press outlet. The bagasse that had accumulated into a presscake was separately collected. The liquor and bagasse were analyzed bythe same procedures described above in Example 4. The liquor was foundto contain 4.23 weight % fines (biomass solids), based upon the totalweight of the liquor. The percentage of the liquid phase from the slurry(i.e., acetone +hexane) that was recovered as liquor was 97.88 weight %.The percentage of biomass solids from the slurry that was recovered aspress cake was 82.56 weight %.

Example 6 Use of a Decanter Centrifuge to Remove Bagasse/Fines from aSlurry

In order to simulate the removal of rubber from a non-Hevea or guayulesource, slurries of varying concentration were prepared. Each slurryutilized a co-solvent mix of 80% weight hexane and 20% weight % acetone.To each slurry was added solids (consisting of insoluble fines, mainlybagasse and dirt/soil, from previous rubber harvesting of guayuleshrub), rubber (obtained from coagulation of a natural rubber latexsourced from guayule shrubs), and resin (mixed soluble resin plusdegraded rubber from previous harvesting of guayule shrub) in amountssufficient to provide the slurry compositions summarized in Table 6.

TABLE 6 (Guayule Slurry Composition) % solids % rubber % resin Slurry 120.8 3.4 1.6 Slurry 2 10.2 3.6 1.6 Slurry 3 7.2 3.8 1.6 Slurry 4 5.2 3.71.6

Each slurry was individually fed into a decanter-type centrifuge(Westfalia Separator Model CA-225-21-000, available from GEA WestfaliaSeparator Group, Elgin, Illinois). Various flow rates were utilized foreach slurry, ranging from 1.0 gallon/minute to 5.5 gallons/minute, asshown in Table 6. The decanter centrifuge utilized is commonly referredto as a bowl-type centrifuge because it has a bowl-like appearance,wherein the bowl allows solids to be lifted out of the liquid. Slurryenters the decanter through a central feed tube and flows into thedistributor chamber. From the distributor chamber, the slurry movesthrough ports into the centrifugation space of the bowl where it isaccelerated to operating speed. The centrifuge was set up with adifferential speed set to 24 rpm and the ring dam was set to 130millimeters; the operating bowl speed was 4750 rpm, equating to a gforce of 2500. Upon operation, the solid materials adhere to the bowlwall by centrifugal force. Within the bowl is a scroll which operates ata slightly faster speed than the bowl shell, thereby continuallyconveying separated solids toward the narrow end of the bowl. Solids aredischarged from the centrifuge through ports in the bowl shell, into thecatch chamber of the housing and are ejected through a solids chute.

Samples were taken of the centrate (miscella) and solids discharge foreach slurry feed and flow rate. Centrate and solids were analyzed for %fines and % solvent, respectively. A portion of the centrate from eachof the slurries at each flow rate indicated in Table 6 was furthertreated to isolate the rubber contained therein by adding additionalacetone until the rubber coagulated (generally rubber coagulation occursat about 1.2:1 hexane/acetone weight ratio). The solvent was decantedoff of the coagulated rubber and the wet rubber that remained wasdesolventized by drying in a vacuum oven at 70° C. Ash and dirtconcentrations within the dried rubber samples were analyzed using ASTMD1278-91. Results are summarized in Table 7. The decanter centrifuge wasable to remove more than 90% of the bagasse contained within eachoriginal slurry mixture, regardless of flow rate, and was also able toproduce a solids content (indicated as % fines in Table 6) of less than1% for each original slurry mixture, regardless of flow rate. Notably inmany instances, the solids content of the miscella was less than 0.5weight % or even less than 0.3 weight %. Changes in flow rates did notproduce a consistent impact on the solvent content of the solidsdischarge.

TABLE 7 Flow Rate % Solvent % Ash % Fines (gallon/ % Fines in in Solid %Bagasse in Dry in Slurry minute) & Miscella Discharge Removal Rubber w/w% (liters/minute) w/w % w/w % w/w % w/w % 5.2 1.0 0.18 69.3 96¹ 1.053.79 2.0 0.24 65.3 1.14 7.57 3.0 0.26 62.7 1.14 11.36 7.2 5.5 0.27 54.9— 1.20 20.82 4.5 0.40 56.3 1.22 17.03 10.2 1.0 0.31 56 97¹ — 3.79 2.00.29 54.4 2.19 7.57 3.0 0.37 60.2 1.37 11.36 20.8 3.0 0.56 53.8 — 1.5611.36 ¹Percentages can be considered as an average from the three flowrates.

Example 7 Hammer Milling, Roll Milling/Cracking and Flaking (FlakeMilling)

Guayule shrub approximately 8-36 months old was harvested and bundledinto bales. The bales were measured to have a moisture content of about20-25%. Bales were fed to a standard wood chipper to reduce the guayulematerial into approximately 1″ sticks. The shredded sticks of guayulewere fed through a hammer mill by hand for further size reduction. Thehammer mill then air conveyed the milled shrub through a fan to acyclone separator. Varied screen sizes for the hammer mill (1″, ½″, ⅛″,and 1/16″) were used. The milled shrub was collected in bins and weighedas it was being produced.

All of the shrub was processed through a Sweco screener with a 20 meshscreen. The screener was used to remove fines from the shrub. It wastested before and/or after milling.

The milled shrub was processed in a cracker (also known as a rollermill), set up to have a differential roll speed of 1:1.1. The rollspacing on the cracker was adjustable. The cracker was fed using avibratory screen feeder and the cracked material was collected in bins.

The cracked material was transferred to a flaker. The flaker had its ownroll feeder, a differential roll speed of 1:1.25 and the roll spacingwas set at 0.012″. Samples of the flaked material were taken andretained for cell rupture analysis and for initial shrub rubber content.Some of the flaked material was retained to be run through the flaker asecond and a third time. The flaked material was collected in bins andweighed. The final flaked material was refrigerated until it was readyto be extracted.

Determination of the % rubber and resin in samples was made using 9-10gram samples of guayule material, soxhlet extracting for 6 hours withco-solvent (31 mL acetone, 170 mL pentane) to solubilize rubber andresin. Solubilized rubber (contained within the pentane phase) wasisolated using methanol coagulation, centrifuging and drying. Morespecifically, 20 mL of the extract from the soxhlet extraction wastransferred to a centrifuge tube and 20 mL of methanol was added tocoagulate the rubber. The tube and its contents was centrifuged at 1500rpm for 20 minutes to separate coagulated rubber from solvent. Thesupernatant within the tube was decanted into a flask and reserved for %resin determination. The tube and its coagulated rubber contents wererinsed with an aliquot of acetone (10 mL) and the acetone was poured outof the tube into the flask containing the decanted supernatant. Theremaining coagulated rubber within the tube was then placed into avacuum oven that had been pre heated to 60° C. and dried under vacuumfor 30 minutes. After cooling to room temperature, the tube was weighedand the amount of rubber therein was calculated. Resin content(contained within the acetone phase) was determined by utilizing theflask containing the supernatant and decanted acetone. The solvent wasevaporated from the flask in a fume hood until near dryness. Theremaining contents were then further dried by placing the flask into anoven at 110° C. for 30 minutes. After cooling, the flask was weighed andthe amount of resin remaining in the flask was calculated. Results aresummarized in Table 8.

TABLE 8 Avg. % Rubber Avg. % (Dry Weight Avg. % Resin (Dry ConditionsMoisture Base) Weight Base) Shredded & 26.79 2.34 6.70 Hammermilled ½″Shredded & 22.29 3.12 6.78 Hammermilled ⅛″ Shredded & 19.67 4.98 6.96Hammermilled ⅛″ & 20 mesh screened & flaked Shredded & 19.52 5.61 7.33Hammermilled ⅛″ & 20 mesh screened & three passes flaked

To the extent that the term “includes” or “including” is used in thespecification or the claims, it is intended to be inclusive in a mannersimilar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “or” is employed (e.g., A or B) it is intended to mean “Aor B or both.” When the applicants intend to indicate “only A or B butnot both” then the term “only A or B but not both” will be employed.Thus, use of the term “or” herein is the inclusive, and not theexclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into”are used in the specification or the claims, it is intended toadditionally mean “on” or “onto.” Furthermore, to the extent the term“connect” is used in the specification or claims, it is intended to meannot only “directly connected to,” but also “indirectly connected to”such as connected through another component or components.

While the present application has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the application, in its broaderaspects, is not limited to the specific details, the representativeapparatus, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicant's general inventive concept.

1-20. (canceled)
 21. An organic solvent-based process for the removal ofrubber from guayule plant matter comprising: a. utilizing a slurrycontaining (i) guayule plant matter, the guayule plant matter comprisingbagasse, rubber and resin; (ii) at least one non-polar organic solvent;and (iii) at least one polar organic solvent, wherein the slurrycontains 10-50% by weight plant matter, 50-90% by weight of (ii) and(iii) combined, and 0.5-10 weight % water from the plant matter, andwherein the at least one polar organic solvent and at least onenon-polar organic solvent are present in relative weight amounts of50-90% and 10-50%, respectively; b. removing a majority of the bagassefrom the slurry to produce a miscella and a first bagasse portionwherein the miscella contains 1-10 weight % rubber and 1-10 weight %resin; c. optionally adding additional polar organic solvent, non-polarorganic solvent or a combination thereof to the miscella to form areduced viscosity miscella where any polar organic solvent and non-polarorganic solvent may be the same or different than those utilized in (a)and where the amount of any additional polar organic solvent that isadded is less than the amount that causes the rubber contained with thereduced viscosity miscella to coagulate; d. utilizing a centrifuge toremove 80-95 weight % of bagasse from the miscella resulting from (b) or(c) (based on the total weight of bagasse present in the miscella) toform a purified miscella and a second bagasse fraction, wherein thepurified miscella contains 0.5-7 weight% rubber and 0.5-8 weight% resin,based upon the total weight of the purified miscella; e. optionallytreating the purified miscella to remove additional bagasse therebyproducing a clarified rubber solution that contains 0.01-1% by weight ofbagasse wherein 90-99% of any additional bagasse that is removed has aparticle size greater than 45 microns; f. increasing the relative amountof polar organic solvent as compared to non-polar organic solvent withinthe clarified rubber solution or the purified miscella so as tocoagulate the rubber; and g. producing solid purified rubber from thecoagulated rubber where when said solid purified rubber contains 0.8weight % volatile matter it also contains 0.05-0.5 weight % dirt,0.2-1.5 weight % ash and 0.1-4 weight % resin; wherein at least (a)-(e)are conducted at a temperature or temperatures of 10-80° C. and apressure of 35 to 1000 kPa.
 22. The process of claim 21, wherein one ormore antioxidants is utilized in the slurry of (a).
 23. The process ofclaim 21, wherein one or more antioxidants is utilized in after (d). 24.The process of claim 21, wherein the (i) guayule plant matter compriseschopped guayule plant matter.
 25. The process of claim 21, wherein themajority of bagasse removed from the slurry in (b) is 60-95 weight % ofthe bagasse contained within the slurry.
 26. The process of claim 21,wherein removing of the majority of bagasse in (b) comprises use of ascrew press.
 27. The process of claim 21, wherein the plant matter inthe slurry has been in contact with the solvents (ii) and (iii) for 0.3to 3 hours prior to (b).
 28. The process of claim 21, wherein thecentrifuge of (d) is a disk centrifuge operated at a speed sufficient togenerate a g force of 4,000-12,000.
 29. The process of claim 21, whereinat least a portion of at least one of the first bagasse portion and thesecond bagasse portion is recycled into the slurry, allowing fortransfer of additional rubber or resin that is associated with thebagasse portion(s) into the miscella that is produced in (b).
 30. Theprocess of claim 29, wherein removing of the majority of bagasse in (b)comprises use of a screw press.
 31. The process of claim 21, wherein theplant matter comprises chopped guayule shrub including bark and woodytissue with no more than 5 weight % of the plant material comprisingleaves.
 32. The process of claim 21, wherein at least (a)-(e) areconducted at a temperature or temperatures of 10-50° C.
 33. The processof claim 22, wherein the chopped plant matter is passed over a meshscreen having a mesh rating of 16 to 30 mesh in order to removeundersize material prior to being added to the slurry.
 34. The processof claim 21, wherein the non-polar organic solvent and any additionalnon-polar organic solvent comprises at least one: alkane having 6 carbonatoms, cycloalkane having 6 carbon atoms, or a combination thereof, andthe polar organic solvent and any additional polar organic solventcomprises acetone.
 35. The process of claim 21, wherein the (ii) atleast one non-polar organic solvent; and the (iii) at least one polarorganic solvent are present in relative weight amounts of 60-85% and15-40%, respectively.
 36. The process of claim 34, wherein the alkanehaving 6 carbon atoms, cycloalkane having 6 carbon atoms or acombination thereof is present in a total amount of 60-85% by weight andthe acetone polar organic solvent is present in an amount of 15-40% byweight.
 37. The process of claim 21, wherein the solid purified rubberof (g) has a molecular weight of 1,000,000 to 1,500,000.
 38. An organicsolvent-based process for the removal of rubber from guayule plantmatter comprising: a. utilizing a slurry containing (i) guayule plantmatter, the guayule plant matter comprising bagasse, rubber and resin;(ii) at least one non-polar organic solvent selected from the groupconsisting of alkanes having from 4 to 9 carbon atoms; cycloalkanes andalkyl cycloalkanes having from 5 to 10 carbon atoms; and combinationsthereof; (iii) at least one polar organic solvent selected from thegroup consisting of alcohols having 1 to 8 carbon atoms; ethers andesters having from 2 to 8 carbon atoms; cyclic ethers having from 4 to 8carbon atoms; and ketones having from 3 to 8 carbon atoms; andcombinations thereof; and (iv) one or more antioxidants, wherein theslurry contains 10-50% by weight plant matter, 50-90% by weight of (ii)and (iii) combined, and 0.5-10 weight % water from the plant matter, andwherein the at least one polar organic solvent and at least onenon-polar organic solvent are present in relative weight amounts of50-90% and 10-50%, respectively; b. utilizing a screw press to remove amajority of the bagasse from the slurry to produce a miscella and afirst bagasse portion wherein the miscella contains 1-10 weight % rubberand 1-10 weight % resin; c. optionally adding additional polar organicsolvent selected from the group consisting of alcohols having 1 to 8carbon atoms; ethers and esters having from 2 to 8 carbon atoms; cyclicethers having from 4 to 8 carbon atoms; and ketones having from 3 to 8carbon atoms; and combinations thereof, additional non-polar organicsolvent selected from the group consisting of alkanes having from 4 to 9carbon atoms; cycloalkanes and alkyl; cycloalkanes having from 5 to 10carbon atoms; aromatics and alkyl substituted aromatics having from 6 to12 carbon atoms, or a combination of additional polar organic solventand additional non-polar organic solvent to the miscella to form areduced viscosity miscella wherein any polar organic solvent andnon-polar organic solvent may be the same or different than thoseutilized in (a) and where the amount of any additional polar organicsolvent that is added is less than the amount that causes the rubbercontained with the reduced viscosity miscella to coagulate; d. utilizinga centrifuge to remove 80-95 weight % of bagasse from the miscellaresulting from (b) or (c) (based on the total weight of bagasse presentin the miscella) to form a purified miscella and a second bagassefraction wherein the majority of the bagasse that is removed has aparticle size of less than 105 microns and wherein the purified miscellacontains 0.5-7 weight% rubber and 0.5-8 weight% resin, based upon thetotal weight of the purified miscella; e. optionally treating thepurified miscella to remove additional bagasse thereby producing aclarified rubber solution that contains 0.01-1% by weight of bagassewherein 90-99% of any additional bagasse that is removed has a particlesize greater than 45 microns; f. increasing the relative amount of polarorganic solvent as compared to non-polar organic solvent within theclarified rubber solution or the purified miscella so as to coagulatethe rubber; and g. producing solid purified rubber from the coagulatedrubber wherein when said solid purified rubber contains 0.8 weight %volatile matter it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight% ash and 0.1-4 weight % resin; wherein at least (a)-(e) are conductedat a temperature or temperatures of 10-80° C. and a pressure of 35 to1000 kPa.
 39. The process of claim 38, wherein the solid purified rubberof (g) has a molecular weight of 1,000,000 to 1,500,000.
 40. The processof claim 38, wherein the plant matter in the slurry has been in contactwith the solvents (ii) and (iii) for 0.3 to 3 hours prior to (b). 41.The process of claim 38, wherein the centrifuge of (d) is a diskcentrifuge.
 42. The process of claim 38, wherein at least a portion ofat least one of the first bagasse portion and the second bagasse portionis recycled into the slurry, allowing for transfer of additional rubberor resin that is associated with the bagasse portion(s) into themiscella that is produced in (b).
 43. An organic solvent-based processfor the removal of rubber from Parthenium argentatum plant mattercomprising: a. utilizing a slurry containing (i) Parthenium argentatumplant matter, the Parthenium argentatum plant matter comprising bagasse,rubber and resin; (ii) at least one non-polar organic solvent selectedfrom the group consisting of alkanes having 6 carbon atoms, cycloalkaneshaving 6 carbon atoms, and combinations thereof; (iii) at least onepolar organic solvent selected from the group consisting of alcoholshaving 1 to 8 carbon atoms; ethers and esters having from 2 to 8 carbonatoms; cyclic ethers having from 4 to 8 carbon atoms; and ketones havingfrom 3 to 8 carbon atoms; and combinations thereof; and (iv) one or moreantioxidants, wherein the slurry contains 10-50% by weight plant matter,50-90% by weight of (ii) and (iii) combined, and 0.5-10 weight % waterfrom the plant matter, and wherein the at least one polar organicsolvent and at least one non-polar organic solvent are present inrelative weight amounts of 50-90% and 10-50%, respectively; b. removing60 to 95% by weight of the bagasse from the slurry to produce a miscellaand a first bagasse portion wherein the miscella contains 1-10 weight %rubber and 1-10 weight % resin; c. optionally adding additional polarorganic solvent selected from the group consisting of alcohols having 1to 8 carbon atoms; ethers and esters having from 2 to 8 carbon atoms;cyclic ethers having from 4 to 8 carbon atoms; and ketones having from 3to 8 carbon atoms; and combinations thereof, additional non-polarorganic solvent selected from the group consisting of alkanes havingfrom 4 to 9 carbon atoms; cycloalkanes and alkyl; cycloalkanes havingfrom 5 to 10 carbon atoms; aromatics and alkyl substituted aromaticshaving from 6 to 12 carbon atoms, or a combination of additional polarorganic solvent and additional non-polar organic solvent to the miscellato form a reduced viscosity miscella wherein any polar organic solventand non-polar organic solvent may be the same or different than thoseutilized in (a) and where the amount of any additional polar organicsolvent that is added is less than the amount that causes the rubbercontained with the reduced viscosity miscella to coagulate; d. removing80-95 weight % of bagasse from the miscella resulting from (b) or (c)(based on the total weight of bagasse present in the miscella) to form apurified miscella and a second bagasse fraction, wherein the purifiedmiscella contains 0.5-7 weight% rubber and 0.5-8 weight% resin, basedupon the total weight of the purified miscella; e. optionally treatingthe purified miscella to remove additional bagasse thereby producing aclarified rubber solution that contains 0.01-1% by weight of bagassewherein 90-99% of any additional bagasse that is removed has a particlesize greater than 45 microns; f. increasing the relative amount of polarorganic solvent as compared to non-polar organic solvent within theclarified rubber solution or the purified miscella so as to coagulatethe rubber; and g. producing solid purified rubber from the coagulatedrubber wherein when said solid purified rubber contains 0.8 weight %volatile matter it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight% ash and 0.1-4 weight % resin; wherein at least (a)-(e) are conductedat a temperature or temperatures of 10-80° C. and a pressure of 35 to1000 kPa.
 44. The process of claim 43, wherein (b) comprises use of ascrew press.
 45. The process of claim 43, wherein (b) comprises use of acounter-current extractor.
 46. The process of claim 43, wherein (d)comprises use of a centrifuge.